US2812375A - Power clamp for furnace electrode - Google Patents

Description

NOV. 5, 1957 5 w ET AL 2,812,375

POWER CLAMP FOR FURNACE ELECTRODE 3 Sheets-Sheet 1 Filed June 20, 1955 INVENTORS I HEA/QY s. NEW/ ALL BY PETER J. Wy/VNE nus/e macwys 1957 H. s. NEWHALL EI'AL POWER CLAMP FOR FURNACE ELECTRODE 3 Sheets-Sheet Filed June 20, 1955 INVENTORS NEW/LL BYPEE/Q J. IWlV/VE HENRY 6.

# W40 Ju THE/R ATTUQNE G I II United States Patent POWER CLAMP FOR FURNACE ELECTRODE Henry S. Newhall, Glenshaw, and Peter J. Wynne, Pittsburgh, Pa., assignors, by mesne assignments, to Mc- Graw-Edison Company, a corporation of Delaware Application June 20, 1955', Serial No. 516,618

4 Claims. (CI. 13-16) The present invention is concerned generally with the supporting and positioning of electrodes used with electric melting, smelting and refining furnaces. More specifically the invention is directed to a novel, eificient form of power-operated clamp for supporting large, preformed electrodes and the positioning thereof in operative relation to the furnace.

Electric melting, smelting and refining furnaces employ in their operation one or more electrodes which are suspended above and extend vertically into the furnace. These electrodes are continuously and accurately positioned relative to the charge withinthe furnace for controlling the power input within close limits. Usually a plurality of electrodes are used, and they are frequently quite large, being as much as thirty. inches or more in diameter and ten or more feet in length. Such electrodes are.

of two well-known types, namely preformed and selfbaking. Such preformed electrodes may be of carbon or graphite. The preformed carbon or graphite rods are harder, and in general have up to a plus or minus 2% tolerance in diameter imposing additional difficulties when using a supporting power clamp which is overcome by the clamp hereinafter described. The, use of multiple electrodes and their individual supporting and adjusting devices is subject to space limitations above the furnace so that a simplified compact form of electrode supporting device is most advantageous.

The principal object of the invention is to provide a power clamp for electrodes which will readily adjust for variations in the diameter thereof, providing good electrical contact and physical support for the electrode.

Another object of the invention is to provide a novel type of a compact actuating mechanism for the power clamp providing adequate pressures between the power clamp and the'electrode.

These and other obejcts will be made apparent in the following specifications and the drawings forming a part thereof, in which:

Fig. 1 shows in elevation the electrode, power clamp and operating mechanism for the power clamp;

Fig. 2 is a transverse section taken along lines lllI of Fig. 1;

Fig. 3 is a transverse section through the actuating cylinder of the power clamp taken along lines IIIIII of Fig. 2;

Fig. 4 is a transverse section through the device along lines IVIV of Fig. 1, illustrating the manner of suspending the power clamp from the operating cylinder;

Fig.5 is a transverse section through the device along lines V-V of Fig. 1, showing application of the contact shoes and the pressure-actuating ring therefor; and

Fig. 6 is an enlarged side elevation of the mechanism taken on the line VIVI of Fig. 1, illustrating the method of applying electrical current to the clamping shoes and cooling water therefor.

Referring now in detailto the'drawings, reference character 1 indicates thedevice generally, comprising a fluidpressnre actuated cylinder 2; suspended by any suitable "ice means such as the cables 3, clamping shoes 4 disposed on diametrically opposite sides of an electrode 5, which shoes are suspended from the cylinder by means of down tubes 6, the shoes being held in contact with the electrode by means of a pressure ring 7 suspended from the cylinder piston by means of operating rods 3.

Referring now to Figs. 1 and 3 of the drawings, the cylinder 1 is comprised of a substantially circular head portion 9, bottom portion 10, and spaced cylindrical side walls 11 and 12 connected with the members 9 and 10. This cylinder may be of a built-up or cast construction, the built-up construction being illustrated in the drawings. The cylinder head and bottom portions 9 and 10 may be of plate construction, each having a ring- shaped portion 13 and 14 welded or otherwise attached thereto, the outer wall 11 abutting against and being attached to the portions 13 and 14 by any suitable means, such as welding, and the inner wall 12 being similarly attached. Within the cylinder and between the side walls 11 and 12 is a suitable piston 15 provided with any suitable packing means, such as the well-known O- rings 16 and 17. In order to provide a fluid-pressure tight connection between the side walls of the cylinder and the top and bottom portions thereof, any suitable packing means may be used, such as the O-rings 18 and 19 as shown. Actuation of the piston 15 is provided by fluid pressure inlets 20 and 21 mounted on the head portion 9 and on the bottom portion 10 respectively of the cylinder. By reason of the cylinder being poweractuated in either direction, the inlets 20 and 21 also serve to exhaust pressure from their respective sides of the piston 15. Operating rods 8 are mounted in the piston 15 by any suitable means such as the threaded connection 22, and move freely through the member 14 and bottom portion 10. A suitable packing 23 is provided about the operating rods 8 in the bottom face of the member 10 as shown. As clearly indicated in Fig. 2, these operating rods 8 are preferably four in number. The head portion 9 and bottom wall 10 of the cylinder may be connected by any suitable means, such as the rods 24 extending through the members and retained in place by nuts 25. The cylinder is suspended above the furnace by suitable means such as the cables 3 passing through the lugs 26 of the head portion 9, and secured in place by suitable means such as the nuts 27. The electrode 5 is disposed within the cylinder inner wall 12, and in spaced relation thereto.

As shown in Figs. 1 and 4 to 6-inclusive, the clamping shoes 4 are suspended by the down tubes 6 from the under side of the cylinder by any suitable means such as bracket 28 which may be a rectangular bar-shaped member as shown, secured to the under side of the cylinder bottom member 10 by fastening members 29, and provided with vertically-extending slots 30 having intersecting openings 31 therein. The down tubes 6 are preferably hollow, having a solid end portion 32 disposed within the slots 39 and having a suitable opening in the portion 32 through which extends a pin 33 disposed within the opening 31 to secure the down tube to the bracket 28. The lower end of the down tubes 6 are connected to the clamping shoes 4 by any suitable means such as the threaded connection 34. The clamping shoe 4 comprises a head portion 35 and a depending face portion 36 provided with a substantially vertical concave inner face 37 corresponding to the diameter of the electrode 5, and a tapered outer face 38 for engagement by the pressure ring 7. The shoe 4 is provided with an internal cavity 39 through which cooling water flows from the down tubes 6, these tubes being two in number for each shoe. One provides a water inlet, and the other a water outlet for the shoe.

' The pressure ring 7 is suspended from the piston 15 by means of the operating rods 8. The pressure ring is a hollow cylindrical member having an outer face 40 and a tapered inner face 41 corresponding to the tapered face 33 of the clamping shoes 4. The pressure ring adjacent its outer periphery is provided with an internal cavity 42. At least two of the operating rods 8 are preferably hollow and are provided with water inlets 43 and water outlets 44, suitable water-carrying conduits 45 and 46 being connected to the respective inlet and outlet. The water flows through the cavity 42 of the ring 7 to provide water cooling when necessary. As shown in Fig. 5 of the drawings, the clamping shoes 4' adjacent the outer periphery of the head portion 35 are provided with offsets 47 providing clearance for the operating rods 8.

Electrical power is supplied to the electrode 5 through the clamping shoes 4 from the down tubes 6 by means of a clamp 48 to which are attached the cables 49 and 50. The clamp 48 may be of the usual two-piece construction having indentations therein to embrace the down tubes 6 and clamped together by any suitable means, as by bolts 51. The power cables 4? and 50 may be of the well-known type having a central tube carrying the electrical power to the clamp, and a concentric outer hollow tube having connections with the down tubes 6. Water flowing through the outer portion of the tubes 49 and 50 is carried into and away from the down tubes 6 by means of the jumper connections 60.

Referring now to the operation of the device, it is normally suspended above the furnace by means of the cables 3, which extend upwardly to a control device, not shown, which lowers the power clamp and electrode, as the electrode is consumed, for the purpose of controlling the power input to the furnace. After a sufiicient portion of the electrode protruding from the clamp has been consumed, the power clamp is released and the electrode lowered through the clamp the necessary distance, and the power clamp re-engaged with the electrode. When changing the relative positions between the electrode and the clamp, a suitable device (not shown) is connected with the upper end of the electrode to support it while the power clamp is released from the electrode and moved to a new clamping position on the electrode. The releasing and re-positioning of the power clamp relative to the electrode is accomplished rapidly, and in the case of a continuously-operated furnace the preferred method would be to first independently support the electrode in operating position as aforesaid, thereafter release the power clamp from the electrode, and move the clamp upwardly relative to the electrode to the new clamping position by means of the cables 3.

Referring now to Figs. 1 and 3 of the drawings, and

assuming that the electrode is being supported by the clamp, fluid pressure entering beneath the piston 15 of the cylinder 1 through inlet 21 maintains an upwardlydirected force on the pressure ring 7 by means of the operating rods 8 to retain shoes 4 in good electrical contact with the electrode, and to exert sufficient pressure thereon to maintain it in fixed relation to the shoes. When it is desired to move the clamp relative to the electrode, the electrode 5 is first temporarily independently supported by means (not shown), and thereafter fluid pressure within the cylinder beneath piston 15 is exhausted from the cylinder, and fluid pressure is admitted above the piston 15 through inlet 2%) to move the piston downwardly, carrying with it the operating rods 8 and clamping ring 7. As the tapered surface 41 of the pressure ring moves downwardly, it is released from the shoes 4, permitting the shoes to swing free of the electrode. The down tubes 6 have limited pivotal movement on the supporting pins 33 for this purpose. The entire clamp, including cylinder, shoes and pressure ring, is then moved upwardly relatively to electrode 5 by means of the cables 3. Fluid pressure is again admitted to the cylinder beneath piston 15 and exhausted from the cylinder above piston 15 for moving the piston, operating rods and pressure ring 7 upwardly relative to shoes 4, and

forcing the shoes inwardly against the electrode to provide the necessary electrical contact and physical support between the shoes and the electrode. Thereafter the temporary electrode supporting means is released from the electrode and downward feed of the electrode is continued through the cables 3.

The power clamp under discussion is used with electrodes of considerable length in proportion to their diameter, and the diameter of the electrodes is upwardly to thirty inches or more. These electrodes are therefore quite heavy, and when of the preformed type, are quite rigid. Considerable pressure must therefore be exerted by the shoes upon the electrode, both for the purpose of making good electrical contact, and providing physical support. As previously stated, the electrodes have a commercial tolerance up to plus or minus 2% in the diameter, so that the degree of pressure necessary to provide physical support, as well as electrical contact by means of the clamping shoes may vary from electrode to electrode of the same commercial diameter and at positions spaced along the length of the electrode. By reason of the cylinder and contained piston encircling the electrode in spaced relation thereto, the area of the piston exposed to pressure within the cylinder increases as the diameter of the electrode increases. There is therefore adequate pressure available at all times to exert the necessary cooperation between the pressure ring and the clamping shoes to secure the desired electrical contact and physi 'al support for the electrode. 7 V

The power clamp may be used in connection with furnaces having either a closed or open top, depending upon the particular operations to be carried out within the furnace. When used with a closed top furnace the power clamp is usually sufficiently protected from the heat of the furnace with water cooling of the current carrying members. When, however, the clamp is used in connection with an open top furnace, it is usually desirable to water-cool other portions or all of the clamp. As shown in Figs. 1 and 6 of the drawings, both the clamping shoes and the pressure ring are cooled by a continuous flow of water through the down tubes 6 and the support rods 8. In the case of severe operating conditions it may also be found desirable to water-cool the cylinder 2. This may be accomplished in a variety of ways (not shown in the drawings). One suitable method would be to enclose the outer side wall 11 and the cylinder bottom wall It with a hollow jacket through which an available cooling medium such as water is continuously circulated.

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

We claim:

1. In a power clamp providing physical support for and good electrical contact with large furnace electrodes, in combination, a cylinder having spaced inner and outer walls, a passageway extending axially through said cylinder for reception of the electrode, a pair of clamping shoes disposed below the cylinder and positioned for applying opposing pressures about the periphery of the portions of the electrodes disposed between them, means suspending the shoes from the cylinder for lateral movement relative to the electrode, a pressure ring enclosing said shoes and movable relative thereto in a direction axially of the electrode in moving the shoes into contact with the electrode, a reciprocal piston within the cylinder, and a plurality of members connecting the pressure ring with the piston for concurrent movement therewith.

2. A furnace electrode supporting and feeding device, comprising a ring-s p d ylinder having a vertical cen tral passageway through which the electrode extends, a reciprocal piston within the cylinder encircling the passageway and movable reciprocally in a direction axially of an electrode disposed therein, clamping shoes pivotally suspended from the cylinder and positioned about the periphery of the electrode extending through said cylinder, a pressure ring encircling said shoes and movable relative thereto axially of the electrode in moving the shoes into clamping engagement with the electrode, and means suspending the pressure ring from the cylinder piston for movement concurrent therewith.

3. In a power clamp providing physical support for and electrical contact with large preformed furnace electrodes, the combination of a ring shaped cylinder and correspondingly shaped piston therein having aligned central openings through which the electrode extends and is movable in a direction axially thereof, suspension means connected with the said cylinder providing controlled vertical movement thereto in a direction axially of the electrode, clamping means suspended from the said cylinder for selective peripheral engagement with the electrode, pressure applying means associated with the clamping means and movable relative thereto in a direction axially of the electrode in effecting engagement between and release of the clamping means and electrode, a connection between said pressure applying means and piston effecting controlled reciprocal movement of the pressure applying means relative to the clamping means and electrode, and means for supplying electrical energy to the electrode through the clamping means.

4. The power clamp as defined in claim 3 wherein the clamping means comprises a pair of members having an inner face corresponding to the contour of a portion of the periphery of the electrode and an outer face inclining upwardly and outwardly from the bottom of the member, and the pressure applying means comprises a ring-shaped member having an inner peripheral face inclined to correspond to the outer face of the clamping members, said ring member being connected with the cylinder piston.

References Cited in the file of this patent UNITED STATES PATENTS

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