US2911455A - Electrode clamp - Google Patents

Description

NOV- 3, 1959 s. M. J. oLssoN ETAL 2,911,455

ELECTRODE CLAMP 5 Sheets-Sheet 1 Filed April 13, 1956 b 1111 a 4 4 02 3M A. 7./ 5, 6./ 5 ///MrW,H|h-hwv AAAAA 5 7 I i OHm 9 5 7/ 6J .n 4 3 8 w 5 :v 6 M M ll.

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5. M. J. OLSSON ET AL ELECTRODE CLAMP 5 Sheets-Sheet 2 A14-m: t

NOV- 3, 1959 s. M, J. oLssoN ETAL 2,911,455

ELECTRODE CLAMP Filed April 13, 1956 5 Sheets-Sheet 5 RNEYS.

Nov. 3, 1959 Filed April 13, 1956 S. M. J. OLSSON El' AL ELECTRODE CLAMP 5 Sheets-Sheet 5 AUnited States Patent ELECTRODE CLAlVIP Sven M. J. Olsson, Mount Vernon, and Vassili Martinson, New York, N.Y., assignors to Sunrod Manufacturing Corporation, New York, N.Y., a corporation of Delaware Application April 13, 1956, Serial No. 578,110v

9 Claims. (Cl. 13 16) The present invention relates to clamps for electrodes and particularly clamps for large electrodes such as those used in electric arc type smelting furnaces.

Such electrodesare sometimes more than four feet in :diameter and carry a very heavy current. In use these electrodes feed down into the furnace as they are consumed or burned away in operation. As the electrode moves down, the clamp approaches the charge and must be raised and repositioned on Athe electrode for con tinued feeding.

It is most desirable, becauseof the high currents involved, to construct a clamp which grips the electrode firmly over a substantial area and has a uniform contact pressure around the electrode to minimize losses due to resistance and assure that the current load is evenly distributed over said contact area, thus preventing localized overheating of the contact surfaces. It is desirable to have the clamp power operated because of the very substantial forces involved with large electrodes and controlled from a point outside of the furnace because of the high temperature adjacent to the topv of the furnace where it is dilicult for a man to work. In order to achieve a uniform contact pressure the clamp must accommodate itself to irregularities in the shape of the electrode and this is accomplished by a multiplicity of flexibly mounted shoes and by equal clamping force applied to each shoe.

The present invention has the following objects:

' ('a') To produce a clamp which can be readily power operated and controlled from a point outside of the furnace.

(b) To produce a clamp which is self-adjusting to compensate for irregularities in shape of the electrode in order to assure that the current load is evenly distributed over said contact area, thus preventing localized overheating of the contact surfaces.

(c) To produce a clamp which although power operated and designed to exercise considerable force will not crack or break the electrode.

(d) To shield the mechanical elements of the device from the high furnace temperature to insure most eicient operation.

In the accompanying drawings we have shown a preferred embodiment of the invention, in which Fig. l is a cross section through 1 1 of Fig. 4;

Fig. 2 is a cross section of the lower portion ofan electrode and electrode clamp taken through 2 2 of Fig. 4; y Fig. 3 is a sectional view through 3 3 of Fig. l;

. Fig. 4 is a sectional View through 4 4 of Fig. l;

Fig. 5 is a view through 5 5 of Fig. l;

Fig. 6 illustrates wedge supports for an electrode clamp equipped with nine shoes; n ",Fig r7 shows thefarrangernent` of wedge supports for electrode clamp equipped with twelve shoes; and

2,911,455 v Patented Nov. 3, 1953 .ICC

In a device of this kind wherein a cylindrical electrode is gripped between clamps or shoes a symmetrically arranged three point contact or its equipvalent is desirable because it evenly distributes the pressure around the electrode. Three point contact, using only three shoes, may be practical for relatively smallvelectrodes but for large ones this limited number of contact shoes does not afford sufficient area of contact to support the considerable weight and transmit the high currents used. If three contact areas are merely increased in size to compensate for the larger diameter of the electrode, it follows that the area of contact becomes so large that each such area cannot adjust itself and compensate for irregularities in the surface and shape of the electrode. For these reasons it is necessary that large electrodes have more than three contact shoes and it is desirable toV use some number which is a multiple of three, such as six, nine or twelve shoes. When more than three are used, some means for balancing and equalizing the pressure of the various shoes on the electrode should be utilized. The present invention is directed to a clamp which has a larger number of shoes than three, such as Y six, nine or twelve. The embodiment of the invention illustrated in Figs. 1-5 illustrates the use of six contact n shoes.

2 and 4. They are arcuatein shape to accommodate` the inside surface of each shoe to the outer surface of the electrode. Each shoe is supported on two electrical conductors 5 which are disposed vertically and extend upwardly from the Shoes to a bus ring 6, made up of a pair of tubular rings 7 and 8 joined together by clamps 9, which is electrically connected to a source of current (not shown). The bus ring 6, the conductors 5 and the y shoes 1 are attached together into a strong unit which the operation of the clamp.

is designed to move vertically a short distance'in relation to the remainder of the electrode clamp. Current is carried from the bus ring to the shoes by means of the conductors 5.

The electrode clamp is built up of various elements connected to a hollow circular suspension ring 10. Hung from this ring is a water-cooled mantle 4. This is deysirably made in two sections, an upper and a lower section, indicated at 4a and 4b, respectively. Each is independent of the other except that they are connected together by pipes and guided by band 11. With this construction the lower portion of the mantle which is subjected to high heat may be replaced without replacing the upper portion of the mantle. On the inside of the lower portion of the mantle near the bottom thereof is a reinforced annular portion shown at 12. The function of this reinforced portion of the mantle will be described more in detail hereinafter.

The clamping shoes 1 are designed to be moved vertically as heretofore ydescribed and this motion is translated into lateral or transverse clamping action by means of Wedge surfaces acting on the shoe. The preferred construction includes an inclined wedge face on the outside surfaces of each shoe, a suspended vertically movable wedge (with a corresponding slope) between each shoe Y 3 and a cooperating pressure surface `on the inside of the mantle.

In the embodiment shown in Figs. l-5, there are three wedge faces lon the outside of each shoe. One of these 'is shown at 2i). As heretofore pointed out, the inner wall of mantle 4b is equipped with a reinforcing pressure ring 12. This furnishes a pressure surface on the inside of the mantle. Between this pressure ring 12 and inclined faces of `each shoe 1 is a wedge unit W. Each such unit consists of three wedges such as the one illustrated at 22 (Fig. 2). These wedges are arranged on a horizontally arcuate supporting plate P hung midway its length from a suitable rod as will be described. The three wedges on the unit cooperate with the three inclined wedge face surfaces on the adjacent shoe. These Wedges are all the same and only one will be described. On the inner side of each wedge 22 is a sloping surface 23 which is complemental to face 20 on the shoe 1. On the outer side of the wedge 22 the surface is arranged 'as a vertical one, as shown at 24, and designed to coopv erate with the vertical surface on the inside of the reinforcing ring 12. In the embodiment shown in Figs. 1-5 which illustrates six shoes there are also six wedge units W (Fig. 4). It is desirable to place rollers or balls between the wedges 22, the shoes 1 and the mantle 4 to decrease friction. The wedge units W are suspended'for a limited vertical movement in order to produce an equal pressure between each shoe and the electrode, as will be more fully described hereafter.

For a clamp with six shoes, as illustrated in Figs. 1-5, `the wedge units are supported on mechanisms such as that shown in Figs. 2, 4 and 5. Each wedge unit is suspended on a rod, as shown at 30a and 30h (see Figs. 2, 4 and 5) and each rod in turn is pivotally attached to a lever as shown in Fig. 5. Rod 30a is pivoted to lever 31a and rod 30b to lever 31b. Lever 31a is pivoted at 32a to the xed suspension ring 10. The free end of the lever 31a rests on the right side of a balance lever 34 pivoted in the middle at 35 to the ring 10. Lever 31b is pivoted to ring 10 at 32b and its right end rests on the left side of lever 34. Adjacent wedgesv are thus arranged in pairs and it is clear from the mechanism illustrated in Fig. that if one wedge unit of a pair is drawn down further than the companion unit, the latter will be moved upwardly because of the balance arrangement furnished by the pivoted lever 34. As a result each pair of units is balanced, one against the other, so that neither one can exert a greater pressure on its cooperating shoe and adjacent mantle wall than the other companion unit. With each pair of wedge units balanced, one against the other, and with six shoes, we attain a result which is substantially the same as a three point pressure support but with a large shoe area.

Fig. 6 diagrammatically illustrates wedge supports for a clamp equipped with nine shoes. Suspension ring supports the wedge units in groups of three each. One of such groups is shown in Fig. 6. The units are illustrated at the bottom of the gure at 40a, 40b and 40C.

They are supported on rods 41a, 41b and 41e, respectively, which in turn are attached to levers on the ring 10. Rod 41a is hung midway to the length of lever 44a which is pivoted to ring 10 at 45a. Rod 41C is hung midway to the length of lever 44C which is pivoted to ring 10 at 45o. Rod 41b is hung from the middle ofl lever 49 as shown. Between rods 41b and 41e is a balance lever 47C pivoted on ring 10 at 48C. Between rods 41a and 41b is a balance lever 47a pivoted on ring 10 at 48a. The right end of lever 44a rests on the left end of lever 47a and the left end of lever 49 rests on the other end of lever 47a. The left end of lever 44e rests on the right end of lever 47e and the right end of lever 49 rests on the left end of lever 47C. If any of the wedge units of the group moves down relatively to the other two units, the other two are moved up. This action, of course,

. 4 tends to wedge the upwardly moving units tighter between their shoes and the mantle ring.

Fig. 7 diagrammatically illustrates an arrangement of wedge unit supports for an electrode holder equipped with twelve shoes. In this construction it will be seen that there are four units marked Sila, Silb, 50c and 50d. These are supported in pairs on balance type cross arms 51a and 51h. The centers of these arms 51a and 51b are supported by rods 52a and 52h attached at their upper ends to pivoted levers 53a and 53b, respectively. Each of these in turn is pivoted at one end to the ring 10, as shown at 54a and 5412. The free ends of the levers 53a and 53b are supported on a balance arm 55 pivoted at its center 56 to the ring 10. In this construction it will be seen that pairs of wedge units are balanced against each other, that is, one pair is balanced against another pair, so that four units are in balance, one against the other, and with a total of twelve shoes this gives substantially the equivalent operation of three point contact or suspension.

As heretofore mentioned, because of the large size of electrodes, the weights involved and the heat generated in the furnace, it is desirable to have this clamping mechanism worked by power. A power mechanism for moving the shoes vertically is preferably a hydraulic mechanism and in a clamp with six shoes, such as that illustrated in Figs. 1-5, three hydraulic power cylinders and pistons are symmetrically arranged around the circumference of the clamp. One of these is shown at 59 in Figs. 1 and 5. Invthe embodiment shown, each of these power units consists of a cylinder 59 with a piston operating therein. The piston rod is shown at 60. The lower part of the cylinder 59 is supported on and pivoted at 62 to a stationary arm 61 which is attached to the vring 1i). Another pair of stationary arms 63 support a Vertical guide plate 64. A depending arm 65 from the bus bar clamp 9 contacts this guide plate 64 and moves up and down thereon for the purpose of centeringand guiding the vertically movable bus bar. The lower portion of this arm is provided with a suitable nubbin 66 which is electrically insulated so that current will not ow from the bus bar to the plate 64.

A pair of parallel pivoted arms 70 are pivoted at their lower end on the stationary arms 63. These arms 70 are spaced apart and at their upper end are joined by a. suitable pivot pin 71 to which is pivoted a pair of transverse arms 73. At their outer end arms 73 are pivotally connected to piston rod 60 as shown at pivot point 74 and at their inner ends pivotally connected at 76 to arm 75 which is insulatedly xed to the top of bus bar clamp 9. With this arrangement of piston, cylinder and linkage, it is obvious that when liquid under pressure is supplied to the underside of the piston, piston rod 60 moves upwardly and the bus bar 6 moves downwardly carrying With it the shoes 1.

The shoes 1, the conductors 5 and the bus bar are all insulated from the remaining elements of the clamp so as to prevent leakage of current. Inaddition, it is desirable to insert insulator links 78 in rods like those shown at 30a and 30b in Fig. 2 and similar supporting rods in Figs. 6, 7 and 8.

Looking at Fig. 1, pipes 80 are designed to carry the weight of the part 4b of the mantle. Pipes 80 also supply the lower part 4b of the mantle with cooling `liquid and for the same purpose cooling liquid connections (not shown) are provided for the upper 4a portion of the mantle to thus maintain a circulation of coolant throughout the mantle. Coolant is also circulated through the series of pipes shown at 83. It will be seen in Figs. 1 and 2 that these are located under the Wedges and arranged from the lower edge of the mantle to a `point near the bottom of the shoes. They will serve to `protect the shoes and wedges from the intense heat of the furnace.

Three supporting lstraps 84 are shown and may be used to support the clamp.

'j" 'Ih'erei'are 'sr'ne modifications which may be 'made to the# embodiments'described and illustrated which are, nevertheless,'withinfthe contemplationof the broader aspects of this invention. i n,

With wedge surfaces such as those illustrated in the drawings and the clamp supported from the straps 84, the *weightvof the electrode tends to move the shoes 1 downwardlyand -thus aid in the clamping of the shoes on ,the'electrode If vthe-slope of the wedge surface on the shoesand the wedges-are in the ropposite direction to that illustrated, 4it would then be necessary to raise the bus bar and the shoes to produce a clamping action. With this construction the weight of the electrodes would not assist in the clamping action, in fact, the weight would have the opposite effect. However, a rather smooth clamping action occurs and a very quick release.

With wedge surfaces such as those illustrated in the drawings and the electrode clamp supported from the straps 84, the weight of the electrode tends to move the shoes downwardly and thus aid in the clamping of the shoes on the electrode. If, however, the clamp is supported from the bus ring 6, it would then be necessary to force the suspension ring (Fig. 1) upwardly and the parts suspended from it, such as the mantle 4, wedges 22, to produce a clamping action. With this construction the weight of the electrodes would not assist in the clamping action, in fact, the weight would have no effect. However, a rather smooth clamping action occurs and a quick release.

In operation the embodiment shown in Figs. 1-5 produces an even clamping shoe pressure on the electrode despite inequalities in the surface of the electrode and despite the fact the electrode may not be perfectly cylindrical. This is accomplished by interposing the suspended or floating wedge unit between the shoes and the inner surface of the mantle, as schematically illustrated in Fig. 8. Looking at that figure, it will be seen that as the shoes 101 are moved downwardly they will come in contact wtih the electrode (not shown) and the wedges 103 and move the latter outwardly until they in turn contact the inner surface of the mantle 104b. Further downward movement of the shoes will cause the wedges to move downwardly in proportion to the pressure exerted between the various wedge surfaces. If one shoe encounters resistance sooner than another, maybe due to a small raised portion on the electrode, this shoe, wedge and mantle will tighten up, the wedge tending to move downwardly with the continued motion of the shoe which, due to the balance arm 104 mounted on suspension ring 110 will move the companion wedge upwardly into a tightening relationship with its corresponding shoe and the mantle wall. Thus the downward movement of one shoe-wedge combination will tend to tighten the companion shoe-wedge combination because of the seesaw or balance effect of the lever 10S. This means a balance is maintained between the two shoes of each pair.

We claim:

l. An electrode clamp comprising six arcuate conducting shoes arranged in a circle for clamping engagement with the surface of an electrode, wedge means for each shoe adapted to move it into engagement with the electrode, each of said wedge means including a wedge face associated with a shoe, means for moving all of said wedge faces longitudinally and together, a complementary wedge slope for each wedge face movable relatively to the surface of said wedge face and to each other and means for interconnecting some of said wedge slopes so that movement of one will cause movement of another but in the opposite direction.

2. An electrode clamp comprising a plurality of arcuate conducting shoes arranged in a circle for clamping engagement with the surface of an electrode, wedge means adapted to move each shoe into engagement with the electrode, said wedge means including a vertically movable wedge' face associated witheach shoe, a corni plementary wedge slope for each shoe movable relatively lto the surface of said wedge face, and means for connecting, adjacent wedge slopes in pairs so that thev connected wedge slopes are adapted to move in opposite directions but equal distances.

- 3. In an' electrode clamp assembly of the class having a supporting framework, a mantle attached to said framework and adapted to surround said electrode, clamping shoes arranged inside saidmantle and adapted to grip said electrode and wedge rmeans for each shoe between said shoe and mantle adapted to move said shoe into clamping relation to said electrode, the combination of means for moving said shoes longitudinally of said electrode, and means for supporting and interconnecting a plurality of said wedge means on said framework to permit said wedge means to move longitudinally of said electrode and relative to said mantle and shoes and to each other during the initial electrode gripping operation, said last mentioned means comprising a horizontal balance lever pivoted on said framework and adapted to support said Wedge means so that as one wedge means is drawn downwardly during the clamping operation another will move upwardly.

4. An electrode clamp comprising a framework, a plurality of conducting shoes supported on said framework and arranged for clamping engagement with the surface of an electrode, a ring surrounding said shoes, a wedge between each shoe and said ring for moving said shoes into clamping engagement with said electrode, means for moving said shoes relative to said framework and longitudinally of said electrode, and means for supporting said wedges on said framework in groups to permit one wedge in a group to move longitudinally relative to another wedge in said group.

5. In an electrode clamp assembly of the character having a supporting framework, a mantle adapted to surround said electrode and clamping shoes adapted to grip said electrode, the combination of a reinforcing ring surrounding said shoes, wedges between said shoes and ring adapted to move said shoes inwardly toward the axis of said electrode to grip the same, means for moving said shoes longitudinally of said electrode and mantle, means on said framework for supporting and interconnecting said wedges independentlyof said shoes so that some of -said wedges will move upwardly when others move downwardly as said shoes are moved into gripping position with said electrode, said last named means including balance arms pivoted on said framework and connected to a plurality of said wedge means.

6. In an electrode clamp assembly of the character having a supporting framework, a mantle adapted to surround said electrode, clamping shoes adapted to grip said electrode, the combination of a reinforcing ring surround ing said shoes, wedges between said shoes and ring adapted to move said shoes inwardly toward the axis of said electrode to grip the same, means for moving said shoes longitudinally of said electrode and mantle, and means for supporting said wedges on said framework in groups so that when one wedge in a group moves longitudinally of said electrode during movement of said shoes in the gripping operation another wedge in the same group will move in the opposite direction.

7. The electrode clamp of claim 6 wherein each said group of wedges consists of three adjacent wedges supported on said framework so that they are adapted to move in opposite directions as said clamping shoes engage said electrode.

8. The electrode clamp of claim 6 wherein each said group of wedges consists of four adjacent wedges supported on said framework so that they are adapted to move in opposite directions as said clamping shoes engage said electrode.

9. An electrode clamp assembly of the class having a supporting framework, a mantle attached to said framework and adapted to surround said electrode, clamping shoes arranged inside said` mantle and adapted to grip said electrode and wedge means for each shoe Abetween said shoe and mantle adapted to move said -shoe into clamping relation to said electrode, the combination of means for moving said shoes longitudinally of said electrode, and means for supporting and interconnecting a plurality of adjacent Wedge means on said framework to permit said wedge means to move longitudinally olf said electrode and relative to said mantle and shoes and in opposite directions one to the other during the initial 8 electrode gripping operation, said last named;V means including balance arms pivoted on said framework and connected to a plurality of `said wedge means.

References Cited in the tile of this patent UNITED STATES PATENTS Nissan Nov. 21, 1944`

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