US3354255A - Means for tightening current supply plates on electrodes in electric furnaces - Google Patents

Description

Nov. 2 1, 1967 E. ARCHINAL ET AL 3,354,255 I MEANS FOR TIGHTENING CURRENT SUPPLY PLATES ON ELECTRODES IN ELECTRIC FURNACES 2 Sheets-Sheet 1 Filed June 29, 1964 Nov. 21, 1967 E. ARCHINAL ET AL MEANS FOR TIGHTENING CURRENT SUPPLY PLATES ON ELECTRODES IN ELECTRIC FURNACES Filed June 29, 1964 2 Sheets-Sheet 2 m f r I l y L. I i i 1% My 2 If, w. I F v. I I E W 1% l l b y v N (N I u *2; I I g I i I I \5 I Q I [L I I I United States Patent F 3,354,255 MEANS FOR TIGHTENING CURRENT SUPTLY PLATES ON ELECTRODES IN ELECTRIC FUR- NACES Ernst Archinal, Hermulheim, near Cologne, and Georg Wehlitz, Efieren, near Cologne, Germany, assiguors to Knapsack-Griesheim Aktiengesellschaft, Knapsack, near Cologne, Germany, a corporation of Germany Filed June 29, 1964, Ser. No. 378,535 Claims priority, application Germany, June 29, 1963, K 50,097 11 Claims. (Cl. 13-16) The present invention relates to means for elastically tightening current supply plates on electrodes in electric furnaces.

The supply of current to the electrodes of electric furnaces has always been associated with certain difficulties. Usually, power is supplied thereto through current supply plates contacting the electrode in radial relationship. Depending on operational requirements, the current supply plates are either held in close contact with the electrode or electrode shell, or in loose contact therewith under low contact pressure, so as to permit e.g. necessary interval advancement of the electrode to compensate for electrode consumption, or out of contact therewith. Whatever the specific means used for tightening the current supply plates to the electrode or for loosening them, they are always required to include structures receiving the reaction pressure of the means applying the contact pressure to the current supply plates. Cotters, screw mechanisms, hydraulic or pneumatic pressure may be used as the contact pressure applying means and, e.g. a rope collar or generally a cast collar having a box-like cross-sectional area is used as the means receiving the reaction pressure.

The present invention is based on the observation that considerably more favorable operational conditions can be created for smaller expense by providing a thrust collar comprising at least two groups of a plurality of pipes hinged so as to form a collar extending from hinge to hinge and encircling the electrode so as to be radially spaced therefrom, and by providing a stationary casing receiving the actual pressure-applying means in the group of pipes locally allotted to each current supply plate.

In one embodiment of the present invention, each group of pipes starts with an ends in a hinge joint portion. The hinge portions and the casings have bores for the passage of cooling water, and each group of pipes together with the hinge joint portions and casings fastened thereto forms a separate cooling water circuit.

Each casing is provided with a thrust bolt having an electrically insulated front end portion. The thrust bolt is extended in rectangular relationship with respect to the electrode axis and extended through a bore disposed in the otherwise closed casing in the casing portion facing the electrode. The thrust bolt is movable along its longitudinal axis and shiftable through springs, which rest on a shoulder of the thrust bolt, by turning a threaded bush inserted in an internal thread carved out in the anti-electrode casing portion.

The pipes in parallel relationship, vertically superposed with respect to the electrode axis so as to form a pipe grouping having link members rigidly connecting them disposed therebetween.

The thrust collar is supported by the current supply plates.

In a second embodiment of the present invention, each group of pipes provided with hinge parts at the respective front end and tail end portions thereof comprises two identical, vertically superposed pipes spaced from one another with the casings receiving the actual pressure-applying means being welded therebetween in pipe cut-outs facing each other.

3,354,255 Patented Nov. 21, 1967 In this second embodiment of the present invention, the casing is a unilaterally closed hollow cylinder having a central bore disposed in its bottom portion and an internal thread carved into the opposite open end portion of the cylinder which has recessed grooves disposed at two positions in the cylinder shell which are opposite to one another and is welded between the pipe cut-out provided in the pipes supporting the cylinder.

In the second embodiment, each casing is provided with a shouldered movable thrust bolt arranged in rectangular relationship with respect to the electrode axis, extended through a central packed bore in the bottom portion of the casing and movable along its longitudinal axis. Interposed springs and a screw cap screwed into the internal thread of the casing maintain the thrust collar in position, the front end portion of the springs resting on the shoulder of the thrust bolt and the tail end portion thereof resting on an exchangeable spacer ring immovably fastened to the thrust bolt.

The thrust bolt used in this second variant is electrically insulated and suspended from the supporting ring allotted to the current supply plates.

In both variants, the thrust collars are made of antimagnetic material so as to minimize electric losses.

The invention is shown diagrammatically in the accompanying drawings in which:

FIG. 1 is a cross-sectional view of an electrode and a top plan view of a thrust collar encircling the electrode;

FIG. 2 is a longitudinal section of a hinge part and FIG. 3 is a longitudinal section of the allotted counterpart;

FIG. 4 is a longitudinal section of a casing with the allotted pressure applying means;

FIG. 5 is a longitudinal section taken along line VV of the electrode, the allotted current supply plate and the allotted thrust collar;

FIG. 6 is a longitudinal section taken along line VIVI of the. casing of the second embodiment with the allotted pressure-applying means, and

FIG. 7 is a side view of the casing with portions of an allotted group of pipes.

In FIG. 1, electrode 1 is in close contact with the current supply plates arranged uniformly around the electrode in encircling relationship. One of the current supply plates is shown in the drawing and identified by reference numeral 2. To each current supply plate 2 there belongs an adjustable means applying contact pressure in radial relationship with respect to the electrode, the individual pressure-applying means being interconnected by pipes 21 so as to form a collar, i.e. the thrust collar encircling electrode 1.

As shown in the embodiment represented in FIGS. 1 to 5, each pressure-applying means comprises a casing 3 having a thrust bolt 4 inserted therein which is extended towards electrode 1 and movable along its axis directed towards the electrode axis and forced into contact with current supply plates 2 by adjustable springs applying pressure in radial relationship with respect to the electrode.

The end portion of thrust bolt 4 facing electrode 1 is provided with a special terminal structure 5 which is electrically insulated from thrust bolt 4 by intermediate electrically insulating layers 6 because in operation structure 5 is in contact with the electrically charge current supply plate 2.

Casings 3 have through bores 10 disposed in the horiozntal plane which open into the lumen of pipes 21 so that a cooling medium can be caused to flow therethrough.

A recessed bore in casing 3 (FIG. 4) is provided with a carved nut thread 9 receiving screw socket 8 which in turn receives the axially shiftable thrust bolt 4 having a shoulder 45 and a sealing packing 30 disposed at its may be designed as shown in FIGS.

front end portion, and also receives a pressure spring, e.g. a helical spring. By turning screw socket 8, thrust bolt 4 can be axially displaced, and the contact pressure applied to the current supply plate 2 can be regulated, the thrust collar receiving the reaction pressure.

The thrust collar is composed of several parts, e.g. in FIG. 1 of two substantially similar halves lying in the same horizontal plane, which are hinged. Each hinge comprises two main parts, i.e. the inner hinge part 11 of FIG. 2 and the outer hinge part 16 of FIG. 3, which are fitted into one another in conventional manner and flexibly and detachably connected with one another by a hinge bolt (not shown in the drawing).

The inner hinge part 11 has passageways 14 and 15 for the passage of cooling water. The joints to the annular passageway 15 are outside the sectional plane and therefore are not shown in the drawing. The hinge bolt is extended through bore 12 of bush 13.

The outer hinge part 16 has passageways l9 and 2t) for the passage of cooling water, the joints to annular passageways which again are outside the sectional plane being not shown in the drawing. The hinge bolt which is preferably of conical shape is extended through bores 17 of bushes 18.

As shown in FIG. 1, each of hinge parts 11 or 15 is rigidly connected to a casing 3, e.g. tight-welded thereto. Care should be taken that the bores 10 disposed in casings 3 for the passage of cooling water coincide with the alloted bores 14 or 19 in hinge parts 11 and N. If a two-part thrust collar is used, each of the two halves thereof will thus communicate with a separate cooling water circuit extended from hinge part to hinge part, the cooling water inlet socket being defined in FIG. 1 by reference numeral 27 and the cooling water outlet socket being defined by the reference numeral 28.

FIG. 5 indicates how the thrust collar of this invention is held in altitude position with respect to the current supply plates. Draw-in- bolts 22 and 24, which are hinged through flexible joint 23, serve to suspend the current supply plateshown on a reduced scale from cantilever 29 fastened to protecting pipe which in turn is fixed to the stationary structural part 26, e.g. the furnace housing. At its lower end, the current supply plate is provided with a cantilever 43 which serves as a support receiving casing 3, if necessary through an interposed shim plate 44 permitting adjustment of the altitude position of the casing.

If a two-part thrust collar is concerned, it is assembled by first placing the two halves thereof on cantilevers 43, then fitting hinge parts 11 and 16 into one another and ultimately inserting the hinge bolts into bores 12 and 17. After adjustment of the altitude position of the thrust collar with the aid of shim plate 44, thrust bolts 4 are advanced by turning thread bushes 3 until the desired contact pressure is produced. The thrust collar is loosened and removed in a reverse order of succession.

In the second embodiment of this invention, which is illustrated in FIGS. 6 and 7 and preferably used in furnaces with low base supported electrodes, the electrode is again surrounded by pipe groupings 39 and which open with an end in hinge parts (not shown in the drawing) connecting the pipes so as to form an endless collar. As shown in FIGS. 6 and 7, each pipe grouping comprises two identical pipes 39'and 40 arranged vertically one above the other and spaced from one another. Each pipe grouping starts with and ends in a hinge part which 2 and 3. At least two such pipe grouping 39 and 40 are required so as to form a closed circle, the inner and outer hinge parts being hinged together so as to form aring by means of a hinge bolt, which is preferably of conical shape, and extended through bores 12 and 17 The pipe groupings serve as the support receiving the casings with the pressure-applying means. On places opposite to each other, the casings 31 are provided along two surface lines with recessed grooves 32, and pipes 39 and 40 have corresponding cutouts disposed on sides facing each other, so that the casings 31 can be inserted and welded to the pipes as shown in FIGS. 6 and 7.

In operation, cooling water is caused to flow through pipes 39 and 4t and the allotted hinge parts in a circuit separate for each pipe grouping, and to flow around casing 31. The recessed grooves 32 are intended to obviate undesired throttling of the cooling water flow in pipes 39 and 4d and to ensure intense cooling of casing 31.

The thrust bolt 33 with the allotted shoulder 34 inserted in the bore of casing 31 slides in the bore of the casing and is guided in the casing portion 31 facing the electrode by means of the bore provided with packing 38. The tail end smaller in diameter of thrust bolt 33 is surrounded by springs, preferably plate springs 35, which rest on shoulder 34 and are forced against shoulder 34 by means of spacer ring 36 held in immovable position on thrust bolt 33, e.g. by means of Seeger ring 41. Thesprings are thereby given a certain initial tension which under otherwise identical conditions depends on the thickness of spacer ring 36 and thus can be predetermined as desired by using spacers of variable thickness.

After assembly, thrust bolts 33, springs 35, spacer 36 and Seeger ring 41 will form a unit which is inserted as such in casing 31. Screw cover 37 fully screwed in adjoins spacer 36 and ensures that return movement of the thrust bolt 33 into casing 31 requires out-weighing the force of springs 35. In other words the current supply plates are held in elastic contact with the electrode.

Packing 38 seated in an annular groove disposed in the central bore of casing 31 prevents solids, vapors and gases included in the furnace atmosphere from penetrating into the interior of casing 31.

In the second embodiment of the present invention comprising a thrust collar especially for use in furnaces with low base supported electrodes, the thrust collar is disposed inside the low base electrode support having a cooling water jacket and suspended from the bearing ring receiving the current supply plates. The upper side of pipe 39 has suspension ledges 42 fastened thereto and operatively connected with a corresponding hanger attachment fixed to the bearing ring. Unless the bearing ring itself is electrically insulated, e.g. from the building structure, the attached hangers have to be designed so as to include electrically insulating link members.

The thrust collars advantageously consist of antimagnetic steel in order to keep electric losses low.

The two thrust collar types disclosed in the present invention offer various advantages over the conventional means. Primarily, the weight is inferior to the weight of conventional cast thrust collars which usually have a box-like cross-sectional area. Furthermore, each pipe grouping extending from hinge to hinge represents a single cooling water circuit having a cross-sectional area remaining substantially constant. Cooling water can therefore be caused to flow therethrough at a rate sufliciently high to ensure good heat transfer data and to keep inside pipe soiling low. Hinges l1 and 16 as well as casings 3 or 31 form part of the respective cooling water circuit and therefore need no further thermal insulation. Still further, it is no longer necessary to use special means in order to prevent the hinges and casings from becoming soiled. Assembly and disassembly of the thrust collar are facilitated, and the space requirements are so small that charging devices can be employed in open furnaces equipped with the present thrust collars which in a special form of construction can also be used in closed furnaces having low base supported electrodes.

We claim:

1. An apparatus for elastically tightening current supply plates on electrodes in electric furnaces consisting substantially of a cooled and hinged thrust collar allotted to each electrode concentrically encircling the electrode and provided with adjustable means applying contact pressure to the current supply plates in radial relationship with respect to the electrode axis, which comprises a thrust collar comprising at least two groups of a plurality of pipes complementary to each other so as to form a circle encircling the electrode so as to be radially spaced therefrom; a plurality of hinges connecting the individual pipes so as to form an endless hinged collar, a plurality of casings, each individual casing receiving means applying contact pressure to the current supply plates and rigidly disposed in the individual groups of pipes locally allotted to each current supply plate.

2. An apparatus as claimed in claim 1, which comprises several groups of pipes, each pipe thereof starting with and ending in a hinge; a plurality of hinges connecting the pipes; a plurality of casings receiving the contact pressure applying means; bores disposed in the said hinges and the said casings for the pass-age of cooling water, each group of pipes with the bores disposed in the allotted hinges and the casing forming a separate cooling water cycle.

3. An apparatus as claimed in claim 1, which comprises a plurality of casings; a thrust bolt having an electrically insulated front portion; a bore disposed in the otherwise closed casings in the casing portion facing the electrode; a sealing packing sealing the said bore in the said casing portion, the said thrust 'bolt being disposed in each individual casing in rectangular relationship with respect to the electrode axis and so as to be movable along its longitudinal axis in the said casings and being extended through the said bore in the said casing portion; springs inserted in the said bore and resting with their front end portion on a shoulder of the said thrust bolt; a pivotable screw socket disposed in the said casing permitting movement of the said thrust bolt in the said casing; and an internal thread disposed in the casing in the casing portion opposite to the electrode, the said internal thread receiving the said screw socket which is pivotable therein.

4. An apparatus as claimed in claim 1 which comprises several groups of superposed pipes arranged in parallel relationship with respect to one another, all pipes being embraced by the same hinges and the same casings; and link members -inserted between the superposed pipes so as to rigidly interconnect the respective pipes.

5. An apparatus as claimed in claim 1, comprising two groups of superposed pipes.

6. An apparatus as claimed in claim 1, wherein the current supply plates support the thrust collar.

7. An apparatus as claimed in claim 6, comprising cantilevers attached to the current supply plates receiving the thrust collar casings.

8. An apparatus as claimed in claim 1, comprising several groups of pipes starting with and ending in hinges and consisting of two identical vertically superposed pipes having cut-outs in pipe sections facing each other and receiving the casings with the pressure applying means, the casings being inserted in the said cut-outs and fastened to the said pipes.

9. An apparatus as claimed in claim 8, wherein the casing comprises a unilaterally closed hollow cylinder, a central bore disposed in the cylinder bottom portion facing the electrode, an internal thread disposed in the opposite open cylinder portion, grooved recesses disposed at two cylinder positions opposite to each other, the cylinder being fastened between the cut-outs of the pipes supporting the said cylinder.

10. An apparatus as claimed in claim 9, which comprises several casings, a thrust bolt having a shoulder, the said thrust bolt being extended in rectangular relationship With respect to the electrode axis and being arranged so as to be movable along its longitudinal axis; a bore having a sealing packing and disposed in the bottom portion of each casing; the thrust bolt being extended through the said bore; springs and a screw cover holding the said thrust bolt in position and screwed into the internal thread of the casing; and an exchangeable spacer ring fastened to the said thrust bolt so as to be immovable in one direction, the front end portion of the springs resting on the shoulder of the said hrust bolt and the tail end portion of the springs resting on the said spacer ring.

11. An apparatus as claimed in claim 8, wherein the thrust collar is suspended from a bearing ring allotted to and supporting the current supply plates so as to be electrically insulated therefrom.

References Cited UNITED STATES PATENTS 2,135,408 11/1938 Moore 13-16 2,477,077 7/1949 Moore 1316 2,949,496 8/ 1960 Inglesrud et al. l3l6- 2,632,780 3/1953 Whitehouse 13-16- BERNARD A. GILHEANY, Primary Examiner. H. B. GILSO-N, Assistant Examiner.

Claims (1)

1. AN APPARATUS FOR ELASTICALLY TIGHTENING CURRENT SUPPLY PLATES ON ELECTRODES IN ELECTRIC FURNACES CONSISTING SUBSTANTIALLY OF A COOLED AND HINGED THRUST COLLAR ALLOTTED TO EACH ELECTRODE CONCENTRICALLY ENCIRCLING THE ELECTRODE AND PROVIDED WITH ADJUSTABLE MEANS APPLYING CONTACT PRESSURE TO THE CURRENT SUPPLY PLATES IN RADIAL RELATIONSHIP WITH RESPECT TO THE ELECTRODE AXIS, WHICH COMPRISES A THRUST COLLAR COMPRISING AT LEAST TWO GROUPS OF A PLURALITY OF PIPES COMPLEMENTARY TO EACH OTHER SO AS TO FORM A CIRCLE ENCIRCLING THE ELECTRODE SO AS TO BE RADIALLY SPACED THEREFROM; A PLURALITY OF HINGES CONNECTING THE INDIVIDUAL PIPES SO AS TO FORM AN ENDLESS HINGED COLLAR, A PLURALITY OF CASINGS, EACH INDIVIDUAL CASING RECEIVING

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