US2944099A - Connector for a tiltable electrode furnace - Google Patents

Description

July 5, 1960 P. SERNITZ ET AL CONNECTOR FOR A TILTABLE ELECTRODE FURNACE Filed Dec. 30, 1957 INVENTOR5. P1401. SEEN/7'2 [M/L HOD/4P) United States Patent 2,944,099 CONNECTOR FOR A TILTABLE ELECTRODE FURNACE Paul Sernitz and Emil Hodapp Duisburg Germany, assignors to Demag-Elektromelallurgie G .m.b.H., Duisburg, Germany, a corporation of Germany Filed Dec. 30, 1957, Ser. No..706,125 Claims priority, application Germany Dec. 31, 1956 8 Claims. (Cl. 1310) This invention relates to an arc furnace, and particularly, to improved means for electrically connecting a furnace whose electrodes tilt bodily with the furnace.

It is a general practice to connect the electrodes of an arc furnace to respective phases of a supply transformer terminal through groups of flexible cables. Be cause the electrodes must be constantly adjusted or regulated to establish proper are conditions during furnace operation, and because the electrodes must tilt bodily with the furnace, the flexible cables are made excessively long in order to compensate for changes in distance between the fixed transformer and the electrode connection. An obvious disadvantage of using cables of anything but a minimum length is the increased loss of power in the cables. Another disadvantage to using cables which connect a furnace in the usual way is the damage done to the strands of the cable when subjected to twisting when the furnace is tilted away from the plane of its operating position. Not only do long cables increase power loss and replacement costs, but they also present an unsightly appearance, due to their distance compensating sag, when associated with an electric furnace installation. It has been proposed that these disadvantages be overcome by mounting the supply transformer directly on the tilting furnace platform, but this creates other disadvantages which even outweight those mentioned above.

Accordingly, it is a general object of this invention to improve the means for connecting a tilting electric arc furnace to its source of supply.

Another object is to provide the su ply cables of an arc furnace with a separable connector that allows one portion of the cable to swing bodily with the electrode during tilting of the furnace so that the total length of he cable need not be great enough to account for tilting and the cable will not be twisted or stressed when the furnace is tilted.

Another object of this invention is to provide convenient and quick acting means for connecting and disconnecting an electric furnace from its source when tilting the furnace is to be carried on.

Another more specific object is to provide a furnace supply line with self-aligning separable contacts which are adapted to effect a high pressure, low resistance electrical connection between the source and the furnace electrodes.

Achievement of the aforegoing and other more specific objects will be evident from time to time when proceeding through the following specification.

According to the invention, an electric furnace whose electrodes are both adjustable in a vertical direction and adapted to tilt with the furnace are connected by relatively short cables to a swinging contact that is supported rigidly but remotely from the furnace. The contact, when the furnace is in normal operating position, resides in a guide supported on a wall of the furnace room, for example. In the guide there is another controllable coacting contact from which other short cable links connect the supply transformer. The first, or swinging contact, is provided with means for anchoring it in the guide when 2,944,099 Patented July 5, 1960 the furnace is operating, and the controllable contact is spring-biased into self-aligning high pressure relationship with the first. Hydraulic or pneumatic means are provided for releasing the anchored contact and for removing contact pressure created by the spring when the contacts are to be separated before tilting the furnace.

The invention will now be described more specifically in connection with the drawing, in which:

Fig. l is an elevational view, partly in section and with parts broken away, of an electric furnace supplied 1 by means of the connector constituting the invention; and

Fig. 2 is a partial sectional view taken on the line 2-2 in Fig. 1.

In Fig. 1, only the parts of an electric arc furnace which are necessary to understanding the invention are illustrated. Among these parts is a post 1 which is rigidly affixed with respect to the arc furnace body, not shown, and adapted to tilt therewith in a plane normal to the plane of the drawing. Post 1, as shown, stands on the front side of a mast 2 indicated in dashed lines, the latter of which is adapted to slide adjacent and in parallelism with post 1. On top of mast 2 there is an electrode arm 3 which terminates in a clamp and an electrode engaged thereby, the last two elements of which are not shown but well known to those practicing the art. Arm 3 supports elongated 'bus bars 4 for carrying current to the far right end of the electrode arm which terminates in the electrode clamp, not shown.

It will be appreciated that post 1 and electrode arm 3, together with their associated parts, tilt bodily and in unison in a plane perpendicular to that of the drawing. It will be further understood that electrode arm 3 executes rapidly reversing vertical movements, subject to the influence of an electrode regulating device, not shown, when the furnace is operating.

Although only one phase of an arc furnace is shown, it will be understood that the arrangement thus far described may be duplicated for other phases. At any rate, it will be evident from viewing Fig. 1 that current is supplied to the furnace from a transformer 5 provided with a secondary terminal 6 from which extends short pieces of heavy flexible cable 7. Slightly longer lengths of cable 8 run from the bus bars 4 toward the supply transformer 5 as is evident from the drawing. Cables 8 are adapted to traverse a path lying substantially in the plane of the paper from their solid line position to other intermediate vertical positions, one of which is suggested by the broken lines above the cable.

Aseparable connection is established between the cable lengths 7 and 8 by the interposition of a connector assembly, generally designated by the reference numeral 10, and whose construction will now be described in detail.

It will be seen that the connector assembly 10 comprises an annular, shell-like guide member 11 that passes through a brickior concrete block wall 12 of the furnace room and is anchored by means of suitable flanges which are evident from inspection of the drawing. Guide 11 houses a sliding, controllable contact 13, which may be a circular or square cylinder that is hollowed out to accommodate a compression spring 14 and an operating rod 15. The compression spring 14 is interposed between a backplate 16 and a conical current interchanging end 17 of the contact. Immediately above cylindrical contact guide 11 there is located a pneumatic or hydraulic cylinder 18 in which resides a piston 19 that is adapted to allow the contact 13 to move right under the influence of spring 14 when exhausted and to move the contact 13 to the left in opposition to the influence of compression spring 14 when pressurized. Piston 19 is connected to the operating rod 15 of the sliding contact by means of suitable linkage 20. Sliding contact 13 is provided with a tongue 21 extending through a suitable opening 22 in the bottom of guide cylinder, 11 in order to facilitate connection of the short cable 7.

In guide 11 there is another contact stud 25 which is engaged under high pressure by the sliding contact 13 under the influence of spring 14 when the furnace is oplrating. Contact stud 25 is conical and concave on its current interchanging surface 26 to receive the complementary convex conical surface 17 on the sliding contact. It will be understood, however, that only one of these surfaces need be conicular and that the other may be perfectly arcuate in order to establish a circular line contact at the pointof tangency between the surfaces rather than area contact as is shown.

Normally, contact stud 25 is firmly anchored by means of a wedge 27 that penetrates stud 25 and extensions 28, see Fig. 2, of cylindrical shell 11 on diametrically opposite sides of contact stud 25. As is evident in Fig. 2, when the wedge 27 is withdrawn, stud 25 may swing sidewise out of cylindrical guide shell 11, and through an are lying in a plane parallel to that of wall 12 and in parallel with the swinging plane of post 1 which is supported on the furnace. During furnace operation, when it is desired to anchor contact stud 25 by means of setting wedge 27, hydraulic or pneumatic pressure is removed from a cylinder 29 in which resides a'spring 30 that acts on a piston 31 and transmits axial force along a rod 32 and to the wedge 27. Thus, it is seen that contact stud 25 is anchored by wedge 27 which is removable by piston 31 when it is desired to tilt the furnace.

In order to stabilize contact stud 25 and to support cables 8 during tilting of the furnace, stud 25 is carried on an angle iron bracket 33 that is rigidly affixed to post 1, by welding for example, and connected to the stud by means of an insulating member 34 and means such as cap screws which appear in the drawing.

-When the furnace is operating, the various parts described above take the positions in which they are illustrated. Post 1 and its associated parts lie in a substantially vertical plane as is true of the cables 8 and contact supporting bracket 33. At the same time, contact 25 is firmly anchored by wedge 27 under the influence of spring 30. Likewise the axially slidable contact 13 is strongly biased into high pressure contact relation with contact 25 under the influence of spring 14. The transformer is energized and a complete electric circuit is established between terminal 6 and the furnace bus bars 4.

When it is desired to tilt the furnace, transformer is preferably de-energized and cylinder 18 pressurized on one side of piston 19 to retract sliding contact 13 from registry with anchored contact 25. This frees the contacts from each other and is followed by the step of retracting wedge 27 by pressurizing cylinder 29 to overcome the influence of wedge anchoring spring 30. When this is accomplished, stud 25 is free for swinging sidewise in either direction out of guide shell 11 and from between its overhanging extensions 28. The distance between contact stud 25 and bus bars 4 will remain the same as the contact 25 swings through a plane parallel with the wall 12 and that there need be no change in the amount of sag in cables 8 nor will they be twisted as a result of tilting the furnace.

After the furnace has been tilted to pour a melted charge or for other reasons, the various parts are swung back to their illustrated positions, wedge 27 is reset, and sliding contact 13 is self-aligned and re-engaged with contact 25. The furnace is again ready for operation.

Having disclosed a preferred embodiment of the invention, many obvious modifications will now appear to those skilled in the art. Therefore, it is to be understood that the specific details of the construction disclosed herein are for the purpose of illustration, and not limitation, except as made necessary by the scope of the appended claims.

It is claimed:

1. In combination, an electric furnace having an axially adjustable and tiltable electrode means, a stationary power source, flexible cable means connecting the source with the electrode means, and releasable connector means interposed in the cable, said connector means comprising first and second separable contacts respectively connected to the cables leading to the electrode means and to the source, said first contact being rigidly supported with respect to the electrode means for swinging through an arc in a plane parallel 'with the swinging plane of the electrode means, means for biasing said contacts into high pressure registry with each other when said furnace is in operating position and including means for releasing said first contact for swinging with the electrode means.

2. In combination, an electric furnace having an axilly adjustable and tiltable electrode means, a stationary power source, flexible cable means connecting the source with the electrode means, and releasable connector means interposed in the cable, said connector means comprising stationary support means, a first contact releasably mountedon said support means and connected to a cable leading to the electrode means, said first contact being rigidly and insulatingly supported with respect to said electrode means, a second contact connected to a source cable and constructed and arranged to slide on said support means into and out of electrical engagement with the first contact, actuating meansoperably connected with said second contact for moving the same with respect to the first contact, means for holding said first contact and including means for releasing said holding means to alow said first contact to swing from its support through an are lying in a plane parallel with the swinging plane of the electrode.

3. The invention according to claim 2 wherein said support means constitutes a fixedly mounted guide shell member in which said contacts are mounted and said shell member is provided with an opening through which said first contact may depart.

4. The invention according to claim 2 wherein said first .and second contacts are provided with opposite current interchanging portions constructed and arranged to register with each other when said electrode means are in operating position, said contacts thereby being selfaligning with each other.

5. The invention according to claim 2 wherein said contacts are provided with complementary conical current interchanging portions constructed and arranged to register one within the other when they are electrically engaged. v

6. The invention according to claim 2 wherein said holding means includes spring biased wedge means projecting through a part of said support means and said first contact, and said releasing means comprises a fluid operated piston operatively connected to said wedge means for overcoming the bias thereon and for retracting said wedge means from the swinging path of said first contact when the electrode means are being tilted.

7-. In combination, an electric arc furnace having electrode means that tilt therewith, a stationary power source supplying the electrode means, flexible cable means in circuit with the electrode means and swingable therewith, releasable connector means interposed between said source and said cable means, said connector means comprising a fixed support means, a first contact mounted in said support means and rigidly and insulatingly attached to said electrode means for swinging therewith through an arc transverse to the support means and lying in a plane parallel to the swinging plane of the electrode means, means engaging said first contact and holding it in its support means against said second contact when said furnace is not tilted and including means-for releasing said first contact for swing-ing with said electrode means, a second contact slidably mounted on said support means and flexibly connected with the source, and actuating means operatively connected with said second contact for effecting high pressure against said first contact when said electrode means is in operating position and for relieving the pressure when said electrode means source, said first separable contact being secured to said is to be tilted. electrode and tiltable therewith, and means for releasably 8. In combination, an electric furnace having an axialsecuring said contacts in high pressure registry with each ly adjustable and tiltable electrode means, a stationary other when said furnace is in operating position.

power coflduotor means comm sa'ld s'tatlona'vry 5 References Cited in the file of this patent power source with the electrode means, and releasable connector means interposed in said conductor, said con- UNITED STATES PATENTS nector means comprising first and second separable con- 1,209,842 Hunt Dec. 26, 1916 tacts respectively connected to the portions of said con- 2,202,224 Moore May 28, 1940 ductor means leading to the electrode means and to the 10 2,728,895 Quackenbush et a1. Dec. 27, 1955

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