US2071937A

US2071937A - Clamp for electric arc furnace electrodes

Info

Publication number: US2071937A
Application number: US94644A
Authority: US
Inventors: Payne William Harvey
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-08-06
Filing date: 1936-08-06
Publication date: 1937-02-23
Anticipated expiration: 1954-02-23

Description

Feb. 23, 1937. w. H. PAYNE 2,071,937

CLAMP FOR ELECTRIC ARC FURNACE ELECTRODES Filed Aug. 6, 1936 2 Sheets-Sheet l Feb. 23, 1931. H, P N 2,071,937

CLAIP FOR ELECTRIC ARC FURNACE ELECTRODES Filed Aug. 6, 1936 2 Shoots-Sheet 2 lln,

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Patented Feb. 23, 1937 UNITED STATES PATENT OFFICE CLAMP FOR ELECTRIC ARC FURNACE ELECTRODES 9 Claims.

An electric arc furnace to which this invention applies is such as may be used for the melting and/or refining of metals, as, for example, steel, iron, and alloy metals, ferrous and nonferrous. In such an electric furnace electric heat is applied by arcing to scrap and slag, the current being taken into the furnace through graphite or carbon electrodes which, in turn, are clampsupported to separate movable electrode arms 10 which, in turn, slide up and down columns or like members fastened to the side of the furnace shell or parts thereof.

In the operation of an electric arc melting furnace, the carbon or graphite electrodes grad- 16 ualiy wear away at the bottom end in the furnace. This means that each electrode has to be slipped down in its clamp three or more times per day. Once or so a day a new section of electrode must be screwed to the one which has been slipped almost down to the top of the electrode clamp on the arm. At the present stage of the art, the operator has to climb up on top of the hot electric furnace each time the clamps have to be operated, to slip the electrodes. This is extremely hot work and also takes too much valuable time of electric arc furnace operation, because every time an electrode is slipped, the power has to be shut oil.

With these conditions in mind, the objects of this invention are to provide- (a) A distantly located (from heat) power means which operates the clamp. This power means has to be located away from the heat to prevent the heat from damaging packings, heating the power fluids, or such as are used.

(b) A power operated electrode clamp. This relieves the furnace operator from climbing up on the furnace to adJust the electrodes, in immediate proximity to heat most of the time so ingo tense that it is very hard on the operator.

(c) A much faster operating clamp. saving dollars of valuable (electric heat) furnace time.

(d) A uniform, correct, constantly applied pressure to clamp the electrode. In the art up 45 to the present time there is usually a fixed (at each setting) screw or wedge gripping of a clamp. Graphite and carbon electrodes have almost a neutral co-erhcient of expansion. Therefore, such electrodes gripped in expansible copper,

to plus steel screws, and in terrific heat, though par-- tially water cooled, vary in their hold on the electrode. This causes dirty and burning contacts, and occasionally slipping trouble. When, holding an electrode, my invention constantly applies correct pressure to the clamp, which gives" with the differential thermal expansion and therefore always grips uniformly.

(e) A clamp wh ch has larger and better (three contacting area) grips on each electrode.

(fl Use of an air blast, located around the electrode, directly on the top of each clamp. In all electric arc furnace operations, dust and grit settle on the electrodes. It is very desirable to blow off this dust and grit each time immediately before an electrode is slipped. By so mechanically connecting the air blast valve with the electrode clamp power means, the operator may, with one movement, open the clamp, and also turn on a blast of air into the blast pipe around the electrode, and so clean off the dust as the electrode is slipped down through the clamp.

As will shortly appear, my new elect rode clamp utilizes a. clamping ring which is actuated by suitable connections, and operable by any source of power, or by hand, distantly located from the heat so that each electrode can he slipped quickly as required. The clamps of this invention are designed for use in mounting and suspending the electrodes which are used in any direct arc electric melting furnace. The clamps shown in the attached drawings are as adapted to a well known type of electric arc furnace.

Further objects and details will appear from the description of the invention in conjunction with the accompanying drawings, wherein,-

Figure l is a side elevation of an electric fure nace employing the clamping means of the present invention;

Fig. 2 is a plan view of the same;

Fig. 3 is an enlarged detail partly in section showing the conductor arm and clamp of the present invention;

Figs. 4 and 5 are details showing the action of the clamp in different positions of adjustment; and

Fig. 6 is a sectional elevation taken on line 6 of Fig. 4.

The clamps of the present invention are applied to an electric furnace III of standard construction, having a cover ll into which project a group of three electrodes l2 arranged in triangular relation. Since the electrodes and the clamping mechanism are substantially identical in each case, the description of one will sufiice for all.

Each electrode is surrounded by a circular clamping collar i3 which terminates at each end in an outwardly projecting extension ll, which extensions are secured to the ends of arms it which in unison support the electrode and which are preferably formed of copper, which constitute the conductor for supplying current through the clamping collar and to the electrode. The extensions stand in spaced relation to one another, and between the shoulders where the extensions merge into the collar is located a wedge block I6, the inner face I! of which is curved to conform to the curvature of the collar. The sides l8 of the wedge block extend in convergent relation to one another and bear against the shoulders, so that as the extensions |4 are drawn together and the clamping collar tightened, the wedge block tends to be forced inwardly toward the electrode. The curvature of the clamping collar is such as to afford direct bearing surfaces l9, H], but the collar is cut away on each side in the region adjacent the contiguous shoulder to aiford a clearance 20, so that on the inner side a clamping contact will be afforded solely by the wedge block I6.

The collar I3 is provided onits inner face at the medial point of its curvature with a notch or channel 2|, which somewhat increases the flexibility of the collar at the medial point and permits it to be drawn together into clamping contact with the electrode by the means now to be described.

One of the collar extensions M, at points slightly behind the associated shoulder, is provided with spaced lugs 22 outstanding from the outer face of the extension, which constitute journals for the mounting of a rocker shaft 23 having keyed thereon at its upper end an operating arm 24 adapted to impart rocking move ments to the shaft, which at an intermediate point has keyed thereon an arm 25 set at an acute angle to the operating arm 24 and extending into a slot or recess 25 out through the shoulder of the collar, which affords a clearance for the movements of the arm 25. The arm 25 at its inner end has pivoted thereto the end of a transversely extending link bolt 26 which extends through an aperture 2! in the companion extension M and has mounted on its outer end a half ball block 28 which is held in place by a nut 29.

The arrangement of these parts is such that when the operating arm 24 is thrust outwardly from the position indicated in Fig. 5 to the position indicated in Fig. 4, it will exert a pull on the link bolt 26 which will tend to coact against the rock shaft 23 and thus exert a clamping action tending to draw the collar extensions M together, thereby imparting a clamping movement to the clamping collar, and at the same time the shoulders, acting upon the wedge surfaces afforded by the wedge block IE, will tend to force the wedge block inwardly.

The arm 24 is actuated by a vertically positioned equalizer bar 30 having pivoted thereto at an intermediate point a thrust rod 3| which extends between the arms |5. The equalizer bar at its upper end has an outwardly projecting finger 32 which engages a notch 33 in the end of the operating arm 24, and at its lower end is provided with a boss 34 which is housed within an aperture 35 extending vertically through a tail piece 36 constituting a part of the wedge block IS. The boss 34 has a bearing within a. socket recess 31, so that as a thrust is imparted to the rod 3| it will be distributed through the equalizer bar 30 and serve to actuate the arm 24 and the wedge block in unison, thereby imparting a three-point clamping contact against the electrode.

The thrust rod 3| is preferably actuated by pneumatic or hydraulic pressure, and as shown is provided at its outer end With a piston 38 operating within a cylinder 39 located between the arms l5. Suitable means are provided for admitting pressure to the cylinder 39, so that the three clamps may be operated in unison by suitable controls located at a point distant from the furnace.

In the furnace shown, each pair of arms I5 is connected with a ring shaped mounting 40 which rides upon a standard 4| and may be raised or lowered by means of a counterweighted cable 42 actuated by a motor driven winch drum 43 around which the cable is coiled.

The clamping collar I3 is preferably cored or piped to provide water channels 44 which are connected with a suitable supply of running water for cooling purposes, and, in order to remove any accumulation of dust or grit upon the electrode, each clamping collar is provided with a blast pipe 45 of ring shaped formation which closely encircles the electrode and is perforated at recurrent intervals to provide tangentially discharging jet openings 46. Each blast pipe is preferably provided with a valve 41 which as shown may be tripped by a finger 48 on the thrust rod 3|, as that, as the thrust rod is retracted to release the clamp and permit the electrode to slide downwardly, the blast valve will be opened and an air blast discharged upon the surface of the electrode to remove any coating of dust or other foreign material.

In use, the electrodes will be properly adjusted to depend into the furnace to the intended position, after which the thrust rod 3| will be actuated to set the clamp, and the current will then be turned on in the usual manner for operation of the furnace. Each of the electrodes can be individually lifted by its winch drum 43, but in addition to the regulation thus afforded it becomes necessary at intervals to provide for the down slipping of the electrodes themselves, and this will be accomplished by actuating the clutch mechanism in the manner described and from a distant point, so that the operator will not be compelled to approach the region of extreme heat in making the necessary adjustment.

The degree of adjustment can be regulated to a large extent by permitting the electrodes to slip downwardly through the interval of time necessary to afford the desired slipping movement, at which point the clamp can be instantly set to arrest any further movement. In case, however, the electrode is overfed by the release of the clamp, it can be elevated by the winch drum to the desired degree to bring the end of the electrods to the intended position.

Although the invention has been described with full detail, it is not the intention to limit the claims to the mechanism shown, since modification thereof can be made without materially departing from the spirit of the invention; and it will be understood that the particular means shown for actuating the thrust rod serve merely for purposes of illustration, and that other mechanisms or appliances can be employed for a like purpose, and that the thrust rods can be operated by hand from a distant point where it is inconvenient to employ hydraulic, electric, or pneumatic pressure.

I claim:

1. In a clamp for furnace electrodes, the combination of clamping members adapted to enga e the electrode, and actuating means extending from said clamping members to a point distant from the electrode and adapted to be actuated from said distant point to impart clamping and unclamping movements to the clamping members. and means above the clamping members for discharging a blast against the electrode to remove ioreign particles from the surface of the electrode.

2. In a clamp for furnace electrodes, the combination of clamping members adapted to engage the electrode, actuating means extending from said clamping members to a point distant from the electrode and adapted to be actuated from said distant point to impart clamping and unclamping movements to the clamping members, means above the clamping members for discharging a blast against the electrode to remove foreign particles from the surface of the electrode, and means engaged by the clamp actuating means for regulating the discharge of the blast concurrently with the regulation of the clamping members.

3. In a clamp for furnace electrodes, the combination of a support a clamping collar carried thereby and open at one side and terminating in spaced extensions, a wedge member longitudinally movable with relation to said support and occupying the space between said extensions and adapted to bear against the surface of the electrode, means carried by the support for drawing together said extensions and concurrently imparting a thrust to the wedge member, and connections operable from a distant point for actuating the means for drawing the extensions together and the means for imparting a thrust to the wedge member.

4. In a clamp for furnace electrodes, the combination of a clamping collar open at one side, a link bolt extending across the open side of the clamping collar and having one of its ends in engagement with one side of the open collar, a swinging arm engaging the opposite end of the link bolt, a pivotal mounting for said arm carried on the opposite side of the open clamping collar, and means for imparting swinging movements to said arm to exert tension on said link bolt to draw the two sides of the clamping collar toward one another.

5. In a clamp for furnace electrodes, the combination of a clamping collar open at one side, a link bolt extending across the open side of the clamping collar and having one of its ends in engagement with one side of the open collar, a swinging arm engaging the opposite and o! the link bolt, a pivotal mounting for said am carried on the opposite side the open clampinll collar, means for imparting swinging movements to said arm to exert tension on said link bolt to draw the two sides of the clamping collar toward one another, and a wedge block interposed between the open sides of the clamping collar and adapted to be forced inwardly by a clamping movement of said collar to engage the surface of the electrode.

6. In a clamp for furnace electrodes, the combination of a split clamping collar open on one side and adapted to partially encircle and engage the surface of the electrode, a wedge block located within the open side of the clamping collar, a link bolt engaging one of the sides of the collar, means carried by the other side of the collar for imparting a pull to the link bolt, a thrust rod operable from a point distant from the electrode, and an equalizer bar pivotally mounted at the end of the thrust rod and having one of its ends in engagement with the wedge block and having its other end in engagement with the means for actuating the link bolt for simultaneously drawing in the ends of the split collar and forcing the wedge block inwardly toward the electrode.

'7. In combination with a clamp for furnace electrodes adapted when released to permit slippage of the electrode, a. blast applying element positioned to apply a blast to the electrode in a region proximate to and above the clamp to expel dust from the electrode.

8. In combination with a clamp for furnace electrodes adapted when released to permit slippage of the electrode, a blast pipe located in proximity to and above the clamp and provided with vent openings positioned to direct a blast against the electrode in the region above the clamp toexpel dust from the electrode.

9. In combination with a clamp for furnace electrodes adapted when released to permit slippage of the electrode, a blast pipe of ring-shaped formation carried by and located above the clamp and provided with vent openings directed inwardly for discharging a blast against the electrode in the region above the clamp to expel dust from the electrode.

WILLIAM HARVEY PAYNE.