METAL REMELTING PLANT AND METHOD FOR REMELTING METAL

Description

[0001] The present invention relates to remelting plants for metals, such as vacuum arc furnaces (VLBO, Vacuum Arc Remelting, VAR) and electroslag remelting plants (ESR, Electro Slag Remelting, ESR) that have one or more melting points and a portal design. The systems feature symmetrical force distribution and a consistently low installation height. State of the art

[0002] Various processes and systems for remelting metals are known from the state of the art. These include, for example, vacuum arc furnaces (VLBO / VAR) and electroslag remelting systems (ESR or ESR). They are primarily used in special metallurgy for remelting and refining various metallic reactive or non-reactive materials such as tool steels, nickel-based alloys, titanium, zirconium, etc. To meet the high quality demands of the resulting materials, these systems have been used in recent decades of remelting technology as completely enclosed units, almost always vacuum-tight or even vacuum- and pressure-tight.

[0003] They essentially consist of one or more – usually two – melting points, a supporting structure in the form of a gantry or a cantilevered column, a vertically movable electrode rod guided on it, a scale, and a furnace vessel, which can be designed either as a vacuum vessel or a pressure vessel. The system can be opened and closed using appropriate drives to insert the electrode to be melted and to remove the resulting ingot after melting.

[0004] Systems that utilize a self-supporting column as their supporting structure have the disadvantage that the functionally relevant elements—electrode rod, scale, and furnace vessel—are attached to individual cantilevers on the sides of the column, creating asymmetrical forces on the supporting structure that lead to extremely high bending moments throughout the entire structure. Very often, these bending moments act primarily on the column foundation. With this concept, the electrode rod is also moved by a laterally mounted electrode rod drive attached to the supporting column. This design in particular exacerbates the disadvantages of the systems described above. However, systems of this type also offer an important feature: With a successful design, the system opens and closes without any change in its height. The overall height therefore remains constant.

[0005] Systems that use a gantry as their supporting structure have the disadvantage that their height changes when they are opened and closed. When opened, the height of the system often increases considerably. This disadvantage very frequently means that such systems can only be accommodated in very high factory halls, which leads to high investment costs for the construction of the systems and their peripherals. The advantage of this system concept lies in the symmetrical distribution of forces. The functional components - electrode rod, scale, and furnace vessel - are symmetrically mounted on the two columns forming the gantry and are vertically movable. The forces acting on the supporting structure are therefore also symmetrical in this system concept. Normally, no bending moment is generated in the foundation.

[0006] Another design known from the prior art consists of a portal in which the functional components of the system are arranged symmetrically, and a melting point containing a melting crucible with a very high attachment. The high attachment on the crucible minimizes the height of the open vessel so that the furnace vessel lift required to open the system is minimized, thus only minimally increasing the system height when the system is opened. The disadvantage of this system concept is that the long crucible attachment - often called a spacer or intermediate piece - represents an additional interface between the crucible and the vessel, which negatively impacts overall handling and, above all, the tightness of the system.

[0007] Another system concept known from the prior art is based on the use of a gantry on which the balance and the electrode rod are mounted and beneath which a vertically divided protective gas device consisting of two half-shells and a hood with an electrode rod feedthrough is suspended. This system concept includes a coaxially driven electrode rod, to the upper end of which the electrode rod drive is attached. The electrode rod drive is supported on the underlying balance via two supporting columns arranged symmetrically to the electrode rod itself, and the balance is in turn attached to the gantry. The electrode rod penetrates through the electrode rod feedthrough and through the hood into the melting chamber formed by the two half-shells. The major disadvantage of this concept is precisely the three-part protective gas device. In practice, it can only be designed to be inadequately vacuum- or pressure-tight.

[0008] For example, CN 102 703 725 A discloses an electroslag remelting furnace for individual electrodes weighing 30–120 t. The solution disclosed therein addresses the problems that naturally arise with conventional column support arms when such heavy loads are attached to them. It is proposed to use a horizontal frame-like structure equipped with a driven and a free-running wheel set on one side, which run on a curved rail, and which is attached to a rotating foundation via a turntable on the other side. A tower-like portal structure is built on this, in which the electrode rod holder and the furnace vessel are located. In the upper part of the portal, the portal frame is supported on the rotating foundation side by another pivoting bracing arm.The complex tower structure is pivoted back and forth between a loading position and a melting position via the rotating foundation. As is typical with such gantry structures, the plant height increases when the electrode rod holder is raised. Furthermore, considerable forces act on the electrode rod and furnace vessel holders during pivoting, as they are suspended freely. EP 0 378 764 A1 and CN 101 457 297 A describe other ESR plants. Task

[0009] The object of the invention was to remedy the above-described disadvantages of the prior art. In particular, a generic remelting plant for metals comprising one or more melting points was to be created, in which the compact plant height remains constant during opening and closing, and all forces acting on the supporting structure occur centrally and symmetrically. Furthermore, the plant should be designed to be pressure- and vacuum-tight. Description of the invention

[0010] This object is achieved by a remelting plant for metals and a method for its operation according to the independent claims. Preferred embodiments are the subject of the dependent claims.

[0011] According to the invention, a remelting plant for metals comprises one or more melting points, which are arranged mostly underground in a foundation of the remelting plant, each with a crucible; a furnace portal comprising a first and a second vertical column, which are connected at their upper end to two opposite sides of a horizontal connecting frame and along their height to at least one further frame formed from two brackets, wherein the furnace portal is connected to the foundation in a rotatable manner by the first vertical column and is movable on a curved rail by the second vertical column, the lower end of which is provided with a drive and at least one wheel, so that the furnace portal can perform a pivoting movement over the one or more melting points; a one-piece furnace vessel, open at the bottom, which is vertically movable within the frame formed by the two brackets;Recesses arranged on the sides of the connecting frame that are not connected to the vertical columns; a plurality of locking elements provided on the brackets and capable of fixing the furnace vessel vertically; a scale connected by its underside to the top of the furnace vessel; an electrode rod support structure comprising two variable-length columns, a lower plate attached to their lower end and an upper plate attached to their upper end, the lower plate being connected to the scale and the upper plate engaging the recesses of the connecting frame and being vertically movable therewith;and an electrode rod extending through the lower plate and the upper plate with a coaxial electrode rod drive mounted on the upper plate, the electrode rod comprising an outer tube, an inner tube movable therein, and a spindle arranged in the inner tube, and the electrode rod drive driving the spindle inside the electrode rod. ;

[0012] A key advantage of the remelting plants according to the invention is the one-piece furnace vessel that can be designed to be truly gas- and vacuum-tight. To achieve a low overall height in the prior art plants, the furnace vessel is divided either vertically into two half-shells or horizontally into two vessel sections. However, these half-shell designs never achieve a truly gas- or vacuum-tight state. The horizontal division, in turn, results in more complex handling and higher costs because the lower vessel section must be manufactured multiple times and attached separately to each mold size.

[0013] In remelting plants according to the invention, one or more melting points can be provided in the plant's foundation. These are predominantly located underground and already minimize the required hall height. They can be more than 50%, more than 60%, more than 70%, more than 80%, more than 90%, or more than 95% underground. Preferably, they are completely underground. In this case, the furnace body has a correspondingly designed lower end that allows connection to the completely submerged melting point.

[0014] Each melting point contains a crucible in which the melting process takes place, which can be carried out using either the ESR or VLBO process. A furnace portal, consisting of two parallel vertical columns, is pivotably mounted on the plant foundation. The first of the two columns is pivotally mounted on the foundation, while the opposite second column has a drive with one or more wheels at its lower end, which is supported on a curved rail in the foundation. The melting points are accordingly arranged on a circular path around the portal's axis of rotation, so that their central axis is concentric with the portal's central axis when the portal pivots.

[0015] For the purposes of this application, the term "column" is not limited to a substantially circular-cylindrical shape of load-bearing components, but explicitly also includes other shapes with a high height-to-diameter ratio, particularly in the form of a cuboid, T-beam, or double-T-beam. Likewise, the term is not limited to solid bodies, but also includes hollow bodies, openwork structures, and lattice structures, provided their design is still suitable for fulfilling the required load-bearing static function.

[0016] Most preferably, the pivoting connection of the first vertical column to the foundation is via a large-diameter roller bearing. In principle, the roller bearings can be any suitable type of ball bearing or roller bearing. For example, they can be ball bearings, cylindrical roller bearings, or tapered roller bearings. Preferably, they are ball bearings. This allows for a low-friction and jerk-free pivoting movement of the portal, even with heavy furnace boilers and electrodes.

[0017] At their upper ends, the vertical columns are connected to each other by a connecting frame, with the vertical columns being connected at least once more along their height by two brackets, which form another closed frame approximately at the middle of the portal height. When reference is made to the middle of the portal height, this can refer to the height range from 30% to 70% of the portal height. The height range can also be 35% to 65%, 40% to 60%, or 45% to 55%. The middle can refer to at least 30%, 35%, 40%, or 45% of the portal height. The middle can refer to at most 70%, 65%, 60%, or 55% of the portal height.

[0018] Between the two vertical columns in the frame formed by the stirrups, a one-piece furnace vessel, open at the bottom, is provided, on which a balance rests. A one-piece furnace vessel, in particular, does not have a long crucible top or spacer, thus minimizing potential leak points.

[0019] Preferably, the scale is designed as a gimbal frame on two load cells. This enables continuous weighing during the melting process, allowing the weight of the electrode to be melted to be tracked. The gimbal function also allows the electrode to be aligned in the melting pot by tilting the electrode rod, keeping both the furnace vessel suspended from the scale and the electrode suspended from the electrode rod vertical.

[0020] A lower plate of a frame-shaped electrode rod support structure is attached to the scale. This electrode rod support structure consists of two vertical, variable-length columns and an upper plate on which the electrode rod drive for the spindle in the electrode rod is attached. Driven by the variable-length columns, the lower plate can move vertically along the electrode rod, for which it has a passage. This allows the furnace vessel to be raised without requiring a change in height beyond the length of the electrode rod. The upper plate with the electrode rod drive is installed in two lateral recesses in the supports that form the connecting frame in such a way that it is secured against upward lifting and rests on the lower edges of these recesses in the event of minimal downward movement.

[0021] The electrode rod comprises an outer tube that represents the entire height of the electrode rod and is adapted to the electrode length and the height of the furnace body. The movable inner tube can be extended and retracted by the spindle located within it, thus achieving a telescopic function. The holder for the electrode is then attached to the lower end of the inner tube. This allows the electrode attached to the electrode rod to be lowered into the crucible or the holder to be raised sufficiently so that a new electrode can be attached to it without vertical movement, which would increase the height of the system. The furnace body, in turn, can be lifted along the electrode rod, together with the scale and the lower plate, via the variable-length columns in order to open and close the furnace. For this purpose, the furnace body is equipped with a vacuum-tight bushing at the top.Due to this double telescopic function of the system, all movement paths that are usually outside the system silhouette in state-of-the-art systems are located inside, so that the system height remains the same in any operating state.

[0022] In preferred embodiments, the upper platen is connected to the frame via two horizontally acting drives arranged at right angles to each other. These allow adjustment of the electrode in the crucible by moving the upper platen. The drives can be designed, for example, as electromechanical cylinders or as fluid-operated cylinders. By activating one or the other drive, the upper platen is moved, thereby tilting the electrode rod, which extends with its lower end through the lower platen and is movably mounted via the gimbal frame of the balance. This centers the electrode suspended from it in the mold, as described above.

[0023] The vertical, variable-length columns of the electrode rod support structure can be provided as driven telescopic structures. These can be designed, for example, as hydraulic cylinders or a rack-and-pinion structure. Most preferably, they are hydraulic cylinders. The variable-length columns preferably have a locking function that prevents unwanted length changes during the remelting process.

[0024] The two brackets connecting the vertical columns incorporate a multitude of locking elements that support the furnace body when it is raised. The locking elements can be designed as bolts or cylinders, for example, which can either retract into corresponding recesses in the furnace body to fix its height or serve as a support surface for its lower edge. The number of locking elements depends on their load-bearing capacity or the weight of the vertically movable furnace structure with electrode rod holder and electrode to be supported.

[0025] A method according to the invention for remelting metals in a remelting plant according to the invention according to one of the preceding claims comprises the steps a) Positioning the furnace portal over one of the melting points, b) Raising the furnace body into a raised position by retracting the two variable-length columns of the electrode rod support structure, with the upper plate resting on the lower edges of the recesses in the connecting frame, locking the locking elements to the brackets, and extending the two variable-length columns by a length less than the height of the recesses, so that the upper plate no longer rests on the lower edges of the recesses and the furnace body rests on the locking elements; c) Attaching an electrode made of the metal to be remelted to the electrode rod;d) Placing the furnace body on the crucible by retracting the two length-variable columns of the electrode rod support structure by a length less than the height of the recesses in the connecting frame, so that the upper plate is again supported on the lower edges of the recesses and the furnace body is no longer resting on the locking elements on the brackets, unlocking the locking elements on the brackets, and extending the two length-variable columns until the furnace body is resting on the crucible; e) Extending the two length-variable columns by a length less than the height of the recesses in the connecting frame, so that the upper plate is no longer supported on the lower edges of the recesses and locking the two length-variable columns; f) Remelting the electrode by applying a voltage and adjusting the electrode by extending the electrode rod;g) Opening the crucible by repeating step b) and removing the molten metal. ;

[0026] Most preferably, in step c), the electrode clamped to the electrode rod made of the metal to be remelted is centered in the furnace vessel by means of the horizontally acting drives.

[0027] The method for using the remelting plant according to the invention is explained below by way of example.

[0028] To increase productivity, remelting plants are usually built with two melting points. This design allows personnel to work in parallel at both melting points, with the melting process taking place in one melting point and the second melting point being prepared for the next melt. The preparatory work for the melt in the second melting point includes changing the crucible, inserting the next electrode to be remelted, and, in the case of ESR processes, filling the slag. If necessary, the electrode may also be aligned. The process according to the invention is designed accordingly. The furnace portal is positioned over one of the two melting points, for example, and the furnace body is in a raised position above the new electrode to be remelted, which is inserted in the crucible as usual.The variable-length columns of the electrode rod support structure, which in this example are hydraulic cylinders, are retracted and the locking elements in the form of cylinder bolts are extended so that the furnace body rests on them.

[0029] The clamping mechanism of the electrode rod, which has been extended to the height of the electrode, is now opened, and the stub of the electrode to be remelted is clamped in place. The electrode is then slightly raised by retracting the electrode rod. The electrode is then clamped to the electrode rod, which in turn is supported on the balance, which itself is attached to the furnace body. The two horizontal drives connecting the upper plate to the connecting frame are activated in such a way that the electrode is centered in the furnace body and thus also in the crucible in the melting point by tilting it around the two axes of the balance's gimbal frame, thus preparing it for the upcoming melt.

[0030] The two hydraulic cylinders of the electrode rod support structure are then retracted so that the upper plate of the electrode rod support structure rests on the lower edge of the recesses in the connecting frame and the furnace body is lifted off the locking elements. The relieved locking elements are then retracted. This clears the furnace body's downward travel, and the hydraulic cylinders of the electrode rod support structure extend, tightly fitting the furnace body onto the crucible. The entire load of the furnace body, scale, electrode rod with the attached electrode, and electrode rod drive hangs centrally on the connecting frame during the downward travel of the body and is thus distributed symmetrically across the two portal columns. This creates only vertical compressive forces on the foundation, and no bending moments occur in any of the structural components.

[0031] After the furnace body has been placed on the crucible, the two hydraulic cylinders of the electrode rod support structure are extended far enough to lift the upper plate of the electrode rod support structure from the lower edge of the connecting frame's recesses. The load of the furnace body, scale, electrode rod with the attached electrode, and electrode rod drive are now transferred to the melting point. In this state, the hydraulic cylinders of the electrode rod support structure are hydraulically locked, and melting can begin.

[0032] By extending the electrode rod, the electrode is slowly lowered into the crucible according to the remelting recipe and remelted. Once the melting is complete, the electrode rod is retracted first. Then, the hydraulic cylinders of the electrode rod support structure are also retracted far enough to first place the upper plate on the lower edge of the recesses in the connecting frame and then lift the furnace body vertically along the electrode rod. As soon as the furnace body reaches its highest position, the locking elements are extended, and the movement of the hydraulic cylinders of the electrode rod support structure is reversed. They now extend until the furnace body is placed on the re-extended locking elements.All forces arising during the opening process and during melting always act centrically and symmetrically on the supporting structure of the plant or on the melting point and therefore do not generate bending moments in the foundation or the structure of the plant.

[0033] By lifting the furnace body vertically along the electrode rod and adjusting the length of the columns of the electrode rod support structure, smooth opening and closing of the system is ensured without negatively changing the system height. There is no "growth" of the system – its height is optimally adapted to the electrode length and the required electrode rod stroke. By placing the upper plate in the recesses of the connecting frame or lifting it off it, the furnace portal can be freely suspended above the connecting frame during the system's opening and closing modes, supporting the weight of the furnace body, scale, electrode rod support structure, electrode rod, and electrode. In melting mode, with the furnace closed, the weight of the electrode rod support structure, electrode rod, and electrode is applied to the scale, thus allowing the electrode to be weighed during the melting process. Short description of the characters

[0034] Figure 1 is a perspective view of an inventive remelting plant using the ESR process in a closed state during melting. Figure 2 is a perspective view of a remelting plant according to the invention using the VLBO process in a closed state during melting. Figure 3 is a sectional view of the remelting plant from Figure 1 in open state before melting. Figure 4 is a perspective view of the scale with gimbal frame. Figure 5 is a perspective view of the connecting frame with the upper plate for the electrode rod support structure. Figure 6 is a sectional view of the connecting frame with the upper plate for the electrode rod support structure. Character description

[0035] The figures merely illustrate a preferred embodiment as an example of the invention. They are therefore not to be understood as limiting. In particular, they illustrate useful combinations of features, which, however, can also be used individually or in other combinations.

[0036] Figure 1 shows a perspective view of a remelting plant according to the invention using the ESR process in a closed state during melting. In this example, the remelting plant comprises two melting points (1). The melting points (1) are provided in the foundation of the plant. The melting points (1) contain a crucible (2) in which the melting process takes place. A furnace portal (3), consisting of two parallel vertical columns (4), is pivotally mounted on the foundation of the plant.

[0037] One of the two vertical columns (4) is pivotally mounted on the foundation via a large roller bearing (7). The opposite vertical column (4) has a drive (5) with a wheel (6) at its lower end, which rests on an arcuate rail (8) on the foundation. At their upper ends, the vertical columns (4) are connected to each other by a rectangular connecting frame (9). Furthermore, the vertical columns (4) are connected again at approximately 40% of the portal height via two brackets (10), which form another closed frame.

[0038] Between the two vertical columns (4) in the frame formed by the brackets (10), a one-piece furnace vessel (11) is provided, open at the bottom, on which a scale (12) rests. A lower plate (15) of a frame-shaped electrode rod support structure (16) is attached to the scale (12), which is designed as a gimbal frame (13) on two load cells (14).

[0039] This electrode rod support structure (16) in turn consists of two vertical, variable-length columns (17) and an upper plate (18) to which the electrode rod drive (20) with the electrode rod (19) is attached. The vertical, variable-length columns (17) of the electrode rod support structure (16) are provided here as driven telescopic structures in the form of hydraulic cylinders. The upper plate (18) with the electrode rod drive (20) is installed in two lateral recesses (21) in the supports that form the connecting frame (9) in such a way that it is secured against upward lifting and rests on the lower edges of these recesses (21) in the event of minimal downward movement.

[0040] In addition, the upper plate (18) is connected to the supports of the frame (9) via two horizontally acting drives (22) arranged at right angles to each other. The second drive (22) is shown in Figure 1only partially visible, as it is located behind the electrode rod drive (20) in the viewing direction. Cylindrical bolts are incorporated into the two brackets (10) connecting the vertical columns (4) as locking elements (23), which serve to support the furnace vessel (11) when it is raised.

[0041] Figure 2 shows a perspective view of a remelting plant according to the invention using the VLBO process in a closed state during melting. In this plant, the entire upper part of the plant is identical to the plant using the ESR process from Figure 1 . It differs only in the melting point (1), which is designed accordingly for the VLBO process. In the Figure 2 only one of the melting points (1) is shown.

[0042] Figure 3 shows a sectional view of the remelting plant from Figure 1in the open state in front of the melt. The section runs vertically exactly through the center of the system. The two vertical, variable-length columns (17) of the electrode rod support structure (16) are retracted. The furnace body (11) is suspended in the upper position and is locked in place by means of the locking elements (23). The lower edge of the furnace body (11) is located slightly below the height of the brackets (10). The new electrode (24) to be remelted is already inserted in the crucible (2), which is then clamped to the electrode rod clamp (26) with its stub (25). The double-tube construction of the electrode rod (19) with the spindle inside is clearly visible. This lowers the electrode rod clamp (26) until the stub (25) can be grasped. The electrode rod (19) is then retracted again so that the electrode (24) hangs freely and can be adjusted.

[0043] It can also be seen that in this position the upper plate (18) rests on the lower edge of the lateral recesses (21) in the supports of the connecting frame (9).

[0044] Figure 4shows a perspective view of the scale (12) with gimbal frame (13) in the remelting plant in the closed melting position. This detailed view shows how the electrode rod (19) runs through the lower plate (15) and the vacuum-tight bushing (27) into the furnace vessel (11). The lower plate (15) is connected to the gimbal frame (13) of the scale (12) via the joint (28). The second joint direction of the gimbal frame (13) is formed by the load cells (14). When the variable-length columns (17) are retracted, the furnace vessel (11) with the vacuum-tight bushing (27) slides upwards on the electrode rod (19), guided by the lower plate (15). If the upper plate (18) is moved by means of the drives (22) to align the electrode (24) in the crucible (2), thereby tilting the electrode rod (19), this movement can be compensated by the gimbal frame (13) via the joints (28) and the load cells (14).

[0045] Figure 5shows a perspective view of the connecting frame (9) with the upper plate (18) for the electrode rod support structure (16). In the oblique view from above, the two horizontally acting drives (22), which are arranged at right angles to each other, are now more clearly visible. In this example, these are hydraulic cylinders. In the center of the upper plate (18), on the lantern (29) of the electrode rod (19), sits the electrode rod drive (20). The upper plate (18) engages in the recesses (21) of the connecting frame (9).

[0046] Figure 6shows a sectional view of the connecting frame (9) with the upper plate (18) for the electrode rod support structure (16). The sectional view clearly shows the double-tube construction of the electrode rod (19) and the spindle (30) arranged within it, which is connected to the upper end of the inner tube of the electrode rod (19) via the spindle nut (31). It also shows the fastening of the spindle (30) in the lantern (29) to the electrode rod drive (20). List of reference symbols

[0047] 1 melting point 17 variable-length column 2 crucible 18 upper plate 3 Furnace portal 19 Electrode rod 4 vertical column 20 Electrode rod drive 5 drive 21 recess 6 wheel 22 drive 7 Slewing bearings 23 Locking element 8 rail 24 electrode 9 connecting frame 25 Stub 10 bracket 26 Electrode rod clamp 11 furnace boiler 27 socket 12 Scale 28 joint 13 gimbal 29 lantern 14 Load cell 30 spindle 15 lower plate 31 spindle nut 16 Electrode rod support structure

Claims

1. A remelting plant for metals comprising - one or several melting sites (1), which for the most part are arranged in the underground in a foundation of the remelting plant, with one crucible (2) each; - a furnace portal (3) comprising a first and a second vertical column (4), which are connected on their upper end with two opposing sides of a horizontal connecting frame (9) and along their height with at least one further frame formed by two brackets (10), wherein the furnace portal (3) with the first vertical column (4) is connected with the foundation such that it can be rotated, and with the second vertical column (4), the lower end of which is provided with a drive (5) and at least one wheel (6), can be moved on a curved rail, so that the furnace portal (3) can make a swiveling movement over the one or several melting sites (1); - a one-piece furnace chamber (11), which is open on its lower side and which can be vertically moved within the frame being formed by the two brackets (10); - openings (21), which are arranged on the sides of the connecting frame (9), which are not connected with the vertical columns (4); - a plurality of locking elements (23), which are provided on the brackets (10) and which are able to fix the furnace chamber (11) in the vertical; - a balance (12), which with its lower side is connected with the upper side of the furnace chamber (11); - an electrode rod supporting structure (16) comprising two columns (17) with variable lengths, a lower plate (15) being attached on their lower end and an upper plate (18) being attached on their upper end, wherein the lower plate (15) is connected with the balance (12) and the upper plate (18) is engaged with the openings (21) of the connecting frame (9) and can be moved vertically within them; and - an electrode rod (19), which runs through the lower plate (15) and the upper plate (18), with a coaxial electrode rod drive (20), which is fastened on the upper plate (18), wherein the electrode rod (19) comprises an outer tube, an inner tube being movable therein and a spindle being arranged in the inner tube, and the electrode rod drive (20) drives the spindle inside of the electrode rod (19).

2. The remelting plant according to claim 1, characterized in that the connection of the first vertical column (4) with the foundation, which is such that a rotational movement is possible, is realized by a large-diameter slewing ring bearing (7).

3. The remelting plant according to one of the preceding claims, characterized in that the balance (12) is designed as a gimbal frame (13) on two weighing cells (14).

4. The remelting plant according to one of the preceding claims, characterized in that the upper plate (18) is connected with the frame (9) via two horizontally acting drives (22) being arranged orthogonally to each other.

5. A method for remelting metals in a remelting plant according to one of the preceding claims comprising the steps of a) positioning of the furnace portal (3) over one of the melting sites (1); b) lifting of the furnace chamber (11) into a lifted position by - retracting of the two columns (17) with variable lengths of the electrode rod supporting structure (16), wherein the upper plate (18) is supported on the lower rims of the openings (21) of the connecting frame (9), - locking of the locking elements (23) on the brackets (10), and - extending of the two columns (17) with variable lengths by a length, which is smaller than the height of the openings (21), so that the upper plate (18) is no longer supported on the lower rims of the openings (21) and the furnace chamber (11) rests on the locking elements (23); c) fastening of an electrode made of the metal which has to be remelted on the electrode rod (19); d) placing of the furnace chamber (11) on the crucible (2) by - retracting of the two columns (17) with variable lengths of the electrode rod supporting structure (16) by a length, which is smaller than the height of the openings (21) of the connecting frame (9), so that the upper plate (18) again is supported on the lower rims of the openings (21) and the furnace chamber (4) no longer rests on the locking elements (23) on the brackets (10), - unlocking of the locking elements (23) on the brackets (10), and - extending of the two columns (17) with variable lengths, until the furnace chamber (4) rests on the crucible (2); e) extending of the two columns (17) with variable lengths by a length, which is smaller than the height of the openings (21) of the connecting frame (9), so that the upper plate (18) is no longer supported on the lower rims of the openings (21), and arresting of the two columns (17) with variable lengths; f) remelting of the electrode under application of a voltage and repositioning of the electrode by extending of the electrode rod (19); g) opening of the crucible (2) by repeating of step b) and removal of the remelted metal.

6. The method for remelting according to claim 5, characterized in that in step c) the electrode made of the metal which has to be remelted, which is clamped on the electrode rod (19), is centered in the furnace chamber (11) by means of the horizontally acting drives (22).