US3578893A

US3578893A - Electrical component clamping device in an electromelting installation for metals

Info

Publication number: US3578893A
Application number: US776401A
Authority: US
Inventors: Otmar Kleinhagauer; Wolfgang Holzgruber; Perter Cerwenka; Wolfgang Hladny
Original assignee: Gebrueder Boehler and Co AG
Current assignee: Gebrueder Boehler and Co AG
Priority date: 1967-11-20
Filing date: 1968-11-18
Publication date: 1971-05-18
Anticipated expiration: 1988-05-18
Also published as: JPS4823929B1; CH478465A; BE724157A; CS170101B2; SU388434A3; DE1807040A1; GB1194948A; DE1807040C3; FR1592921A; DE1807040B2

Abstract

A device for establishing an electrical connection with a component to be used, for example, in the continuous casting of metal. The device includes a pair of electrically conductive clamping members which are adapted to clamp the component between themselves. A pair of swing-lever means are respectively swingable about predetermined axes and carry the clamping members. A fluid-pressure means coacts with these swing-lever means to act on them in one direction for pressing the clamping members against the component in an opposite direction for retracting the clamping members away from the component.

Description

United States Patent [72] Inventors Otmar Kleinhagauer;

Wolfgang Holzgruber; Peter Cerwenka; Wolfgang Hladny, Kaplenberg, Austria [21 1 App]. No. 776,401 [22] Filed Nov. 18, 1968 [45] Patented May 18, 1971 [73] Assignee Gebr. Bohler 8: Co. Aktiengesellschaft Vienna, Austria [32] Priority Nov. 20, 1967, Nov. 20, 1967 [33] Austria [31] A10398 and A10397 [54] ELECTRICAL COMPONENT CLAMPING DEVICE IN AN ELECTROMELTING INSTALLATION FOR METALS 4 Claims, 4 Drawing Figs. [52] US. Cl 13/16 [51,] Int. Cl 1105b 7/10 [50] Field ofSeaneh 13/15, 15

[5 6] References Cited UNITED STATES PATENTS 2,249,776 7/1941 Moore 13/ l 6 2,386,260 10/1945 Payne .13/16 3,198,870 8/1965 Simpkin et al. 13/ l 6 3,026,444 3/1962 Slocombe et al. l 3]] 6(X) 3,390,220 6/1968 Wagner I 13/15 Primary Examiner-Bernard A. Gilheany Assistant Examiner-Roy N. Envall, Jr. AttorneyArthur 0. Klein ABSTRACT: A device for establishing an electrical connection with a component to be used, for example, in the continuous casting of metal. The device includes a pair of electrically conductive clamping members which are adapted to clamp the component between themselves. A pair of swing-lever means are respectively swingable about predetermined axes,

and carry the clamping members. A fluid-pressure means coacts with these swing-lever means to act on them in one direction for pressing the clamping members against the component in an opposite direction for retracting the clamping members away from the component.

ELECTRICAL COMPONENT CLAMPING DEVICE IN AN ELECTROMELTING INSTALLATION FOR METALS BACKGROUND OF THE INVENTION The present invention relates to a device for establishing an electrical connection with a given component.

For example, the present invention may be used for establishing an electrical connection with an electrode, baseplate, or the like, as used particularly in installations for continuous casting of metal such as steel by way of melting of electrodes which are made of the metal to be used in the casting period.

It is well known in such installations to provide an electrical connection of the electrical conductors with the metal which is to be melted and which fomis an electrode as well as with the baseplate of the installation used for continuous casting by way of screw clamps made of electrically conductive metal and connected with the electrical conductors. Thus, in the case of continuous casting, an electrode is formed by the metal which is melted within a mold which is open at its'top and bottom, and this mold continuously moves upwardly while the solidified metal becomes continuously exposed at an increasing height below the upwardly moving mold. This cast metal rests on a baseplate which is itself electrically conductive and is connected into the circuit, so that in this way by connecting the electrode, from which the molten metal is derived, and the baseplate into the circuit, it is possible to'provide a closed circuit which will heat the electrode to form from the latter the molten metal which continuously builds during upward movement of the mold to form the continuously cast ingot or block which rests on the electrically conductive baseplate.

In the further development and improvement of continuous casting methods of this latter type, it is required to manufacture steel ingots or blocks, for example, derived from aplurality of steel electrodes which are melted one after the other. During the continuous casting process one steel electrode, as a result of the heat generated with the current which flows electrically therethrough, is melted to such an extent that only a short residual partof the electrode remains, then this residual part of the electrode must be raised up out of the mold, by way of the structure which carries the electrode, and must be replaced with a new electrode which is then introduced into the mold to continue the continuous casting operations with the new electrode. Thus, by lowering the electrode holder which now carries the new electrode, thelatter will be brought into the mold and melted therein.

With electrode changing of the type described above, the screw clamps referred to above must be released from the residual part of the previous melted electrode and then screwed onto the new electrode. In relatively large installations, the screw clamps, because of the large amount of electrical current which flows therethrough,-which maybe on the order of approximately 20,000 A. or more, must be of a large size and quite heavy. As a result, in such installations "the disconnection of the screw clamps from the residual electrode and the fixing of the same to the new electrode is very difficult to carry out.

As the result of unavoidable lack of evenness or smoothness and inaccuracies at the component to which the clamps are connected on the one hand and also as a result of the clamping surfaces of the screw clamps, on the other hand, a uniform engagement of the screw clamps to the electrode or other electrical component cannot be achieved. As a result of this factor, a relatively high current-transmitting resistance is always present between the screw clamp and the component connected thereto. With current magnitudes on the above order of, for example, approximately 20,000.A. or more, there are not only considerable electrical energy losses but also scorching and charring takes place undesirably at the contact surfaces.

LII

SUMMARY OF THE INVENTION It is a primary object of the present invention to provide a device which will avoid the above drawbacks.

Thus, it is an object of the invention to provide a device which will enable an electrical connection to be established with a component of the above general type rapidly and conveniently.

Also, it is an object of the present invention to provide a device which will enable this electrical connection to be opened just as conveniently and rapidly.

Furthermore, it is an object of the invention to provide a device which will reliably assure that when an electrical connection is made the electrical contact surfaces uniformlypress against each other.

In accordance with the invention, these objects are achieved with a device which has a pair of electrically conductive clamping members between which a given component is to be clamped. A pair of swing-lever means are provided for carrying these clamping members, and a fluid-pressure means is situated between and acts on the swing-lever means to press the clamping members toward each other and into engagement with the component or to retract the clamping members away from the component when the electrical connection is to be interrupted. This fluid-pressure means can be either a pneumatic or hydraulic cylinder-and-piston assembly.

It is of advantage if between an'ns of the pair of swing-lever means which are distant from the-clamping members, a spring means, in the fonn of one or more springs, preferably composed of a series of cup springs, acts advantageously through intermediate members on the pair of swing-levers so as to urge them in directions which press the clamping members against the component with which an electrical connection is to be established. Thus, with such an arrangement the fluid-pressure means will act in opposition to the spring means in order to retract the clamping members away from the component during interruption of the electrical connection.

Furthermore, it has proved to be advantageous to situate between the pair of swing-lever means a fixed transverse carrier member on both sides of which a pair of coil springs are respectively situated pressing against the transverse carrier member on the one hand and the pair of swing-lever means on the other hand.

The resistance between the clamping members and the component against which the latter press is particularly low, especially in the case where the clamping members each have a pair of relatively sharp edges each of which is formed between a pair of inclined surfaces which intersect each other at each sharp edge and which in cross section have the configuration of substantially straight lines. With this type of construction it has proved to be of advantage if with the pair of clamping members of this type the elongated relatively sharp edges of one clamping member are respectively in line with those of the other clamping member. Furthermore, particularly advantageous relationships are achieved in the case where the pair of inclined surfaces which define each sharp edge of each clamping member-are situated in planes which include between themselves an angle on the order of l00-l4 0 preferably approximately BRlEF DESCRIPTION OF DRAWINGS The invention is illustrated by way of example in the accompanying drawings which form part of this application and in which:

FIG. 1 is a schematic partly sectional elevation of one possible embodiment of a device according to the invention;

FIG. 2 is a top plan view of-the device of FIG. 1;

FIG. 3 is an end view of the device of FIG. 1, as seen from the left of FIG. 1; and

FIG. 4 illustrates, in a transverse section, how the clamping members of the invention can coact with an electrode instead of with a flat plate, the coaction with a flat plate being shown in FIGS. I3.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings, there are illustrated therein a pair of opposed clamping members 3 preferably made of copper and each having a pair of relatively sharp edges 3'. These relatively sharp edges press against the component I which in the illustrated example is in the form of a flat electrically conductive connecting sheet electrically connected with and extending from the baseplate 1 which is also electrically conductive and on which the continuous casting ingot or the like builds during the continuous casting operations. Thus, the component 1' forms an electrically connecting component for establishing an electrical connection with the baseplate 1, and it is the component 1' which is clamped between the clamping members 3 engaged by the relatively sharp edges 3' thereof. Thus, in an installation for electrically melting metals in connection with continuous casting, such as in the case of continuously casting steel ingots as referred to above, the ingot will build on the baseplate 1, and the screw-and-nut assemblies 2 which also are electrically conductive, serve to connect the component 1' to the baseplate 1. Both this component 1' as well as the baseplate 1 are made of copper.

The relatively sharp edges 3' of both clamping members 3 extend parallel to each other with the pair of edges 3' of one component 3 respectively being aligned with the edges 3' of the other clamping member 3.

Both of the clamping members 3 are cooled by water. The cooling water flows through supply hoses 4 (FIG. 2) into passages 5 respectively formed in the clamping members 3, and the cooling water leaves these passages 5 through the discharge hoses 6.

From one pole of an unillustrated source of current (for ex- I ample, the secondary winding of a transformer) come the pair of fixed conductive bars 7 which extend up to the region of the clamping members 3. Each of the bars 7 is electrically connected with a plurality of bendable bare copper bands 8 which form electrical conductors electrically connected with the members 3, respectively. The copper bands 8 are bent to a substantially U-shaped configuration and are electrically connected on the one hand to the bars 7 by way of the screw fasteners 9 and on the other hand to the members 3 by way of the hexagonal screw members 9. At the end regions of each set of copper bands 8, there are situated, respectively between the several copper bands, intermediate plates 10 and 10'. In-

stead of copper bands 8 it is also possible to use bendable woven wire tapes as the electrical conductors providing the electrical connections between the bars 7 and the clamping members 3.

Each of the pair of clamping members 3 is fixed to an intermediate member 14 by way of a screw member 11 having a hexagonal head. Between each clamping member 3 and the intermediate member 14 which coacts therewith is an insulating plate 13 made of an electrically nonconductive material. Moreover, the screws 11 which are respectively threaded into the intermediate members 14 are respectively surrounded by insulating sleeves 12 so as to be electrically insulated from the clamping members 3.

Each intermediate member 14 has connected to its end face, which is directed away from the clamping member, a holding ring 15 which is fixed to the member 14 by way of screws 16 having at their head ends recesses of hexagonal configuration, for example, so that the'screws 16 which are countersunk into the ring 15 can be threaded into threaded bores which are formed in the intermediate member 14. The interiors of the holding rings 15 are formed with stepped bores providing each ring 15 with an inner shoulder directed toward the intermediate member 14 and overlapping the enlarged head l9 of a pin 17 held assembled with a swinglever means 21 by a nut 20 of hexagonal configuration which is threaded onto a threaded shank portion of the pin 17 which is distant form its head 19.

It is to be noted that each of the pins 17 is provided between its enlarged head 19 and its cylindrical shank 17' with a section 18 whose diameter is smaller than the head 19 and larger than the shank l7, and this portion 18 of the pin 17 extends with clearance through the smaller diameter bore portion of the ring 15 and has its outer shoulder engaging a transverse member 21" of each swing-lever means 21. It is to be borne in mind that the pair of clamping members 3 are mounted and actuated in identical manners with structures which are symmetrical and mirror images of each other, so that whatever applies to the upper clamping member 3 of FIG.-l and the lever structure and other components coacting therewith also applies to the lower clamping member 3 of FIG. 1.

The head end I9 of each pin i7 is provided at its end face which is directed toward the intermediate member 14 with a convex configuration forming part of a sphere, and in addition there is between the ring 15 on the one hand, and the head 19, shank portion 18 and swing-lever 21 on the other hand, a sufficiently great play so that the clamping member 3 will be capable of automatically adjusting itself with respect to the surface of the component against which it presses, such as, for exam ple, the electrical connecting component it, in the illustrated example, which serves to provide an electrical connection between the baseplate 1 and the clamping members 3. Thus, the holding ring 15 and the pin 17 operate in the manner of a ball-and-socket joint.

The pair of swing-lever means 21 are respectively turnable on parallel pivot pins 23 which in turn are held mounted on the housing 22 against axial movement with respect thereto by the holders 24 which coact with pivot pins 23, respectively. Thus, as may be seen from FIGS. 1 and 2, each pin 23 extends through aligned openings in opposite sidewalls of the housing 22, and those ends of the pins 23 which are visible in FIG. 1 projects sufficiently beyond the housing 22 so as to be formed with grooves which respectively receive edges of the rectangular plates 26 which are faxed to the exterior of the sidewall of the housing 22 which is visible in FIG. 1 by way of the bolts indicated in FIGS. 1 and 2. In this way the pins 23 are restrained against axial and rotary movement and serve to support the swing-levers 21 for turning movement about the parallel axes of the stationary pins 23.

A fluid-pressure means is situated between and coacts with the pair of swing-lever means to move the latter. This fluidpressure means may be pneumatic, for example, but in the illustrated example it is hydraulic and includes a cylinder 27 terminating at its bottom end in an extension which receives a pivot pin 28 carried by the lower lever 21 of FIG. 1, so that in this way the cylinder 27 is pivotally connected with this lower lever 21 of FIG. 1. The fluid-pressure means includes a piston 25 slidable within the cylinder 27 and capable of having fluid under pressure act thereon in a well known manner which does not form part of the present invention so that it is not further illustrated. This piston 25 is connected with a piston rod 26 which through a suitable extension is pivotally connected with an upper pivot pin 28 carried by the upper swinglever means 21 of FIG. 1, so that in this way the fluid-pressure means 25, 27 is situated between and operatively connected with a pair of lever means 21.

In addition, a spring means 29 is situated between and acts on the pair of lever means 21 for urging them to turn at their arms which are on the side of pivots 23 opposite from the clamping members 3 in a direction where these latter arms will move apart from each other, so that the spring means 29 acts to urge the clamping members 3 toward each other and into engagement with the component 1'. The spring means 29 takes the form of a stack of cup springs oppositely directed one with respect to the next and having their peripheries engaging each other while all of the stack of cup springs are coaxially aligned so that the annular cup springs are uniformly situated with respect to and surround a common axis along which a guide pin 30 extends so that through this pin 30 the stack of springs 22 are gildfid and maintained in proper cooperative relationship with respect to each other.

An additional spring means formed by a pair of coiled springs 39, which have a common longitudinal axis, is also situated between the pair of swing-levers 21, these coaxial coil springs 39 being situated on the side of the spring means 29 opposite from the fluid-pressure means 25, 27.

Each swing-lever means 21 is formed by a pair of aligned, coextensive lever plate members 21' which are parallel to and spaced from each other in the manner indicated most clearly in FIG. 2, with these members 21' being connected to each other by way of an integral transverse sleeve member 21 through which the pivot 23 for each lever means 21 extends. In addition, at their left ends, as viewed in FIGS. 1 and 2, the pair of lever plates 21 are interconnected by the transversely extending carrier member 21" formed with the bore which receives the shank 17' of the pin 17, as shown most clearly at the left portion of FIG. 1. The pins 28 respectively extend transversely through aligned openings of the lever plate members 21' of the pair of lever means 21, in the manner shown most clearly for the upper pin 28 in FIG. 2, and the extensions of the piston rod26 and the cylinder 27 which arerespectively formed with bores through'which 'thepins 28 also 'pass'are respectively received between the wall components 21' of the pair of lever means 21.

The coaxial stack of cup springs 29 are guided at their inner peripheries by the bar 30 which is of circular cross section and at their exterior peripheries the cup springs are guided by a tubular member 35. The guide bar 30 and the guide tube 35 are respectively fixed at their outer ends with circular end plates 31 and 36, and the spring means 29 is situated between and presses against these end plates 31 and 36. The end plate 31 has an outer extension 32 received between the lever walls 21' of the upper lever means 21 of FIG. 1, and through a bore of the extension 32 extends the horizontal pivot pin 38 which also extends through aligned opening of the lever walls 21' of the upper lever 21, so that in this way the upper end plate 31 is pivotally connected with the lever means 21' in the same way as the piston rod 26.

In a similar manner the lower end plate 36 has a horizontally bored extension received between the walls which form the lower lever means 21 of FIG. 1, and a second pivot pin 38 extends through the bore of the extension which is fixed to end plate 36 as well as through aligned bores of the parallel spaced lever walls of the lower lever means, so that in this way the lower end plate 36 is pivotally connected with the lower lever means of FIG. 1 in much the same way that the cylinder 27 is pivotally connected thereto. Furthermore, the end plate 31 which is fixed to the upper end of the guide bar 30 ha fixed to its outer periphery an outer tubular member 33 which telescopically surrounds the tubular member 35, this tubular member being formed in the region of the end wall 31 with openings 34 which may be used for adjusting purposes as well as for flow of air into and out of the interior space defined by the

tubular members

33 and 35 and the end walls 31 and 36.

The pair of coil springs 39 are respectively situated at their outer ends within recesses 40 which are formed in transverse members extending between and fixed to the walls 21' of the pair of lever means 21 at the outer free ends of the latter distant from the clamping members 3. The inner ends of the pair of coaxial 'coil springs 39 which are directed toward each other are respectively received in end recesses formed in a pair of slide blocks 41. A pair of coaxial pressure pins 42 extend coaxially into the coil springs 39 to be respectively surrounded thereby and these pressure pins 42' are respectively formed with axially extending exterior grooves 42'. The slide blocks 41 are respectively provided with coaxial bores through which the pins 42 slidably extend, and in these bores the slide blocks are respectively formed with axially extending ribs which are slidably received within the grooves 42 so that while the blocks 41 can slide axially along the pins 42 they cannot turn with respect thereto. The pressure pins 42 are formed at the sides of the blocks 41 which are directed away from the springs 39 with threads which extend through hexagonal nuts 44. .The inner ends of the pressure pins 42, which extend inwardly beyond the nuts 44, press against opposed which thus forms a stationary transverse carrier member against which the pair of pressure pins 42 butt at their inner ends. Thus, by adjusting the locations of the nuts 44 along the pins 42, it becomes possible to locate the pair of swing-levers 21 and the clamping members 3 carried thereby in the correct positions and to provide a corresponding prestress for the pair of coil springs 39. Inasmuch as the pair of coil springs 39 form elastic intermediate members, it is possible for the clamping members 3 to adjust themselves with respect to the component clamp end between the members 3 to establish an electrical connection therewith, this component being the plate 1' in the illustrated example.

In order to facilitate the assembly of the above-described elements, the sidewalls of the housing 22 are respectively formed with openings through which the

pins

28 and 38 are accessible, and these openings are closed by removable cover members 46 held in position on the sidewalls of the housing 22 surfaces of a stationary transverse block member 45 which is fixed at, its opposed ends to the sidewalls of the housing 22 and by suitable screws 47.

As is indicated at the lower portion of FIG. 1, the housing 21 is mounted and held in position on any suitable support by way of the threaded studs which extend upwardly from this support through openings in a base flange of the housing 22, and these threaded studs carry the nuts 49 which press downwardly against this flange to hold the housing 22 in position.

- As is apparent from FIG. 4, the construction described above is not only suitable for coaction with acomponent such as the component 1' which is in the form of a flat plate but also this structure can serve to establish an electrical connection with a component of circular cross section such as the electrode 50 which fomts the material which is melted during the continuous casting and which may be made, for example, of steel. Thus, one of the assemblies of the invention may be used to establish an electrical connection with a baseplate and another of the assemblies of the invention may be used to establish a connection with an electrode of a continuous casting assembly of the type referred to above.

Furthermore, it should be noted that with the particular embodiments of the invention described above, each clamping member 3 has its elongated relatively sharp edges 3' respectively formed, for each edge 3', between a pair of inclined flat surfaces having in-cross section the configuration of a straight line and including between themselves the angle or shown in FIG. 1. This angle between the inclined surfaces which define the relatively sharp edge 3' may be on the order of l00-l4 0, and preferably is approximately As contrasted with the conventional clamping screws, the structure of the invention presents the very important advantage of being capable of easy and rapid disconnection from a component such as the residual part of an electrode which remains to be changed for a new electrode, and also in the same simple, rapid manner, it is possible to reestablish the connection with another component, such as a new electrode, which is tightly clamped between the clamping members 3 of the structure of the invention. Also, with the structure of the invention the engaging surfaces between the clamping members and the component with which an electrical connection is established provide a transfer resistance which is substantially smaller than in the case of conventional clamping screws. Thus, the structure of the invention provides, in contrast with conventional structures, the additional advantage of having absolutely no appreciable energy loss at the connection and of preventing, moreover, any scorching or charring of the contacting surfaces in a very reliable manner.

With the structure of the invention, the pair of springs 39 form a spring means which by coaction through the pressure pins 42 with the stationary member 45 serve to situate the pair of swing-lever means 21 at proper positions relative to each other, and the spring means 29 forms an additional spring means coacting with the spring means 39 to urge the pair of clamping members 3 toward each other and into engagement with a component such as the component 1'. The fluid-pressure means 25, 27 can be acted upon with a fluid under pressure so as to oppose the force of the spring means 29 and 39 and pull the right arms of the levers 21, as viewed in FIG. 1, toward each other, so that in this way the clamping members 3 can be moved apart from each other to be retracted away from the component 1'. Also, when pressing against the component l, the direction of action of the fluid-pressure means 25, 27 can be reversedto add its force to that of the spring means for achieving the required high pressure with which the clamping members 3 clamp the component I therebetween.

' We claim:

1. ln an installation for electrically melting metals, a device for establishing an electrical connection with electrodes, baseplates and similar electrically conductive components, comprising in combination,

a supporting frame,

a pair of electrically conductive clamping members adapted to engage an electrically conductive component so that the component is clamped therebetween;

each of said pair of clamping members has a pair of relatively sharp edges which are respectively aligned with the relatively sharp edges of the other clamping member and each sharp edge is defined between a pair of inclined surfaces of substantially straight-line cross section;

a pair of swing-lever means pivotally mounted in said frame and carrying said pair of clamping members, and

fluid-pressure means being respectively pivotally connected at opposite ends to each one of said pair of swing-lever means forswinging the latter either to maintain said pair of clamping members pressed against the component or to retract the clamping members away from said component.

2. The combination of claim 1 and wherein said pair of swing-lever means both have lever anns distant from said clamping members, spring means operatively connected with said arms of said pair of swing-lever means for urging said clamping members through said lever means into engagement with the component, and said fluid-pressure means acting in opposition to said spring means for retracting said clamping members away from the component.

3. The combination of claim 1 and wherein a stationary support is situated between the pair of swing-lever means, and a pair of compression springs respectively situated on opposed sides of said support and engaging the pair of lever means for pressing against the latter to urge the clamping members into engagement with the component.

4. The combination of claim 1 and wherein the inclined surfaces defining each edge are respectively situated in planes which include between themselves an angle on the order of l00l40, preferably an angle of approximately

Claims

2. The combination of claim 1 and wherein said pair of swing-lever means both have lever arms distant from said clamping members, spring means operatively connected with said arms of said pair of swing-lever means for urging said clamping members through said lever means into engagement with the component, and said fluid-pressure means acting in opposition to said spring means for retracting said clamping members away from the component.
3. The combination of claim 1 and wherein a stationary support is situated between the pair of swing-lever means, and a pair of compression springs respectively situated on opposed sides of said support and engaging the pair of lever means for pressing against the latter to urge the clamping members into engagement with the component.
4. The combination of claim 1 and wherein the inclined surfaces defining each edge are respectively situated in planes which include between themselves an angle on the order of 100*-140*, preferably an angle of approximately 125*.