EP3707451A1

EP3707451A1 - Melting furnace with simultaneously rotatable and movable electrode rod

Info

Publication number: EP3707451A1
Application number: EP18807877.8A
Authority: EP
Inventors: Cihangir Demirci; Ros EL-RABATI; David Robinson
Original assignee: SMS Mevac GmbH
Current assignee: SMS Group GmbH
Priority date: 2017-11-08
Filing date: 2018-11-07
Publication date: 2020-09-16
Also published as: JP2021501834A; US20200355435A1; RU2748757C1; KR102437050B1; CA3079360A1; CN111356890A; CA3079360C; BR112020005917B1; US11371779B2; WO2019091994A1; ZA202001387B; WO2019092005A1; BR112020005917A2; KR20200068720A

Abstract

Melting furnace (1), in particular for producing metal alloys by melting alloying constituents, comprising a melting crucible (10), a cylindrical electrode rod (40) with a consumable electrode (41) attached thereto and a power supply (50), which is designed to supply power to the electrode (41) via the electrode rod (40), wherein the electrode rod (40) is rotatable about its own axis and movable along its own axis during the melting process.

Description

Melting furnace with simultaneously rotatable and movable electrode rod

Technical area

The invention relates to a melting furnace, in particular for the production of metal alloys and non-ferrous alloys by melting alloy constituents, with a crucible, an electrode rod with a self-consuming electrode attached thereto, and a power supply adapted to energize the electrode via the electrode rod to supply.

Background of the invention

Melting furnaces are used for the production of metal alloys by melting alloy components and possibly additives. Melting furnaces are known in various designs. They are used both in the remelting of metal by means of an arc under vacuum and in so-called electroslag remelting. The melting process takes place in that an electrode is immersed in a melt and supplied with a so-called melt stream. The melt acts as an electrical resistance, causing the melt to be heated by the melt stream.

The furnace usually comprises a crucible, which may be cold or refractory lined, a furnace hood closing the crucible, and an electrode rod immersed in the crucible by a vacuum and / or gas tight passage in the furnace. The Electrode rod carrying the electrode is connected to a high current power supply.

Since the electrode is gradually consumed - this is referred to as a "self-consumable electrode" - the electrode must be tracked during operation. In order to be able to track the electrode rod with the electrode attached thereto, the system usually has a height-adjustable electrode carriage or a drive technology for holding and moving the electrode rod.

Melting furnaces of the type described above are disclosed, for example, in DE 42 07 967 A1, DE 101 56 966 A1, WO 2013/1 17529 A1 and WO 2014/177129 A2.

In the current process, it is necessary to track the electrode and to precisely control the rate of deposition, for example, to maintain a stable arc. However, not only the immersion depth of the electrode into the crucible affects the melting process, but also the melting mode, i. the geometry and position of the electrode tip.

Presentation of the invention

An object of the invention is to provide an improved melting furnace, in particular for the production of metal alloys and non-ferrous alloys by melting alloy constituents.

The object is achieved with a melting furnace with the features of claim 1. Advantageous developments follow from the subclaims, the following description of the invention and the description of preferred embodiments. The melting furnace is a plant used for the production of metal alloys and non-ferrous alloys by electrical remelting of an electrode, if necessary under vacuum. The melting furnace is designed, for example, as: electroslag remelting unit (ESC) under protective gas or atmosphere with stationary and / or sliding seal; Pressure electro-slag remelting plant (DESU) under different protective gases or process gases with stationary and / or sliding bar; Electro-slag rapid remelting plant (ESSU) with stationary and / or sliding strip for the continuous production of cast or molten strands; Light Arc Vacuum Melting Furnace (LBV); Combination system of the types mentioned, in particular for an ESU system with stand crucible and / or sliding bar and an "Electron Beam Furnace" (EB). It should be noted that the term "smelting furnace" does not in the narrower sense encompass only the "furnace" or crucible, but designates the smelting plant as a whole.

The melting furnace according to the invention comprises a crucible, which is preferably lined cold or refractory. The crucible, designed for instance as a hollow-cylindrical vessel closed at the bottom, is designed for melting alloy constituents, additives, etc. The smelting furnace further comprises an electrode rod having a self-consumable electrode attached thereto and a power supply configured to energize the electrode via the electrode rod, so that melting energy into the molten metal in the crucible, also referred to as a molten pool, sump or Metal bottom is called, can be introduced, for example, between the electrode and the molten metal, an arc is ignitable. The electrode rod is rotatable about its own axis during the melting process and can be moved along its own axis. The rotatability and movability of the electrode rod during the melting process allows a precise tracking and adjustment of the electrode, whereby the stability of the melting process is improved. The mobility is in this case provided in particular along the axial direction of the electrode rod, ie usually in Schwerkraftrichtu ng. In particular, uneven melting of the electrode tip can be compensated by a combination of rotation and lifting / lowering of the electrode.

The mobility of the electrode rod preferably allows an oscillating movement in order to be able to track the electrode rod in an oscillating manner in accordance with the electrode consumption. By oscillating the electrode, the electrode tip is kept constant in the slag bath in a defined range, in particular the distance between the electrode tip in the slag bath and the surface thereof is kept constant.

Preferably, the electrode rod is attached via an electrode holder on an electrode carriage, which is held on a furnace column and guided to the mobility. The furnace column, for example as part of a frame of the melting furnace, allows the modular attachment and guidance of movable components of the melting furnace.

Preferably, the electrode carriage by means of a spindle drive or hydraulic cylinder is movable, the spindle drive is particularly preferably attached to the electrode carriage and one or more motorized, such as electric motor driven spindle nuts, which cooperate with a spindle which extends substantially parallel to the furnace column. In this way, the vertical mobility of the electrode in a structurally simple and reliable and modular way to accomplish. Preferably, the melting furnace has a motor, such as electromotive, rotary drive for rotating the electrode rod about its axis, wherein the rotary drive is preferably mounted on the electrode holder. In this way, the rotatability of the electrode in a structurally simple and reliable and modular way accomplish. In addition, a simultaneous rotation and procedure of the electrode during the melting process is ensured.

Preferably, the electrode rod is electrically connected to the power supply via a current collector, the current collector having one or more contacting means arranged to transfer the current supplied from the power supply to the electrode rod. The current collector can be designed to be compatible for various formats of the electrode rod. The pantograph may have bushings for receiving power lines and / or for protection against damage and dirt. The current collector provides a reliable connection of the electrode to the power supply, even during any rotation and / or any method of the electrode rod. The current collector may be a separate component or, for example, also part of the electrode rod.

The contacting device (analogous to a plurality of contacting devices) can be constructed in various ways, moreover consisting of different conductive and non-conductive materials, as long as reliable contact with the rotatable and movable electrode rod is ensured. Thus, the contacting device may have a receptacle that is electrically connected to the electrode rod and contains a conductive liquid, preferably liquid gallium, in which a current output, which is electrically connected to the power supply, is immersed. Alternatively or additionally, the contacting device one or more brushes, preferably from a graphite-containing and / or copper-containing material, which are in frictional contact with the electrode rod have. Alternatively or additionally, the contacting device may comprise at least one shell element, preferably of a graphite-containing and / or copper-containing material which is in frictional contact with the electrode rod. The shell element can be designed as a ring or ring segment.

Preferably, the furnace has a movable furnace hood, which is adapted to close the crucible, wherein the electrode rod and / or the electrode is immersed in the crucible by a preferably vacuum and gas-tight implementation in the furnace hood. Preferably, the furnace hood is compatible for different crucible dimensions. The performance of the furnace hood allows despite the preferred vacuum and gas tightness, the vertical movement of the electrode rod relative to the crucible. The furnace hood is attached according to a preferred embodiment of a hood car on the furnace column and guided by this. The height adjustment of the furnace hood can be done for example by means of a spindle drive. Preferably, however, the furnace hood is instead mounted by means of a hydraulic cylinder or spindle drive on the electrode carriage, whereby a relative distance therebetween in a hydraulic manner is adjustable.

Preferably, the crucible is attached via a furnace platform on a stage wagon, which is held on the furnace column and guided to the mobility. Thus, the crucible can be attached to the furnace column in a modular manner.

Preferably, the stage wagon is movable by means of a stage spindle drive, wherein the stage spindle drive is preferably mounted on the stage wagon and has one or more motor-driven spindle nuts which are connected to a stage spindle which is substantially parallel to the furnace column runs, interact. In this way, the vertical mobility of the crucible can be done in a structurally simple and reliable and modular way.

Preferably, the furnace has one or more weighing cells which are measuring cells for weighing the weight of the electrode and / or the molten block in the crucible. Preferably, the load cells are installed below the bottom plate of the crucible and / or on the electrode carriage and / or on the stage wagon, particularly preferably below the fusible link. Typically, load cells are installed at the top of the crucible with associated receiving plates. In this case, the measured weight measured values can be falsified by the rotation operation of the electrode. An installation of the load cells below the bottom plate of the crucible, optionally alternatively or additionally on the electrode carriage and / or on the stage wagon, can improve the measurement accuracy in a melting furnace with a rotating electrode.

Although the invention is particularly preferably used in the technical field of production of metal alloys, the invention can also be implemented in other areas, in particular if a self-consuming electrode is used by electrically igniting and maintaining an arc between the electrode and a melt. Specific examples include the electrochemical melting of aluminum, silicon and calcium carbide. The invention is also suitable for producing metal powder for 3D printers.

Further advantages and features of the present invention will be apparent from the following description of preferred embodiments. The features described therein may be implemented alone or in combination with one or more of the features set forth above insofar as the features do not conflict. The following description of the preferred embodiments is made with reference to the accompanying drawings.

Brief description of the figures

FIG. 1 shows a melting furnace with crucible and a rotatable and movable electrode rod.

Figures 2a to 2c show exemplary embodiments of contacting devices for electrically conductive connection of the rotatable and movable electrode rod with a power supply.

Figures 3a and 3b show shapes of the electrode tip and the underlying metal bottom.

Detailed description of preferred embodiments

In the following, preferred embodiments will be described with reference to the figures. In this case, identical, similar or equivalent elements in the figures are provided with identical reference numerals, and a repetitive description of these elements is partially omitted in order to avoid redundancies.

FIG. 1 shows a melting furnace 1 which serves for the production of metal alloys by electrical remelting of an electrode, if appropriate under vacuum. The melting furnace 1 is embodied, for example, as: electro-slag remelting plant (ESC) with stationary and / or sliding seal; Pressure electro-slag remelting plant (DESU) with stationary and / or sliding bar; Electro-slag quick-remelting plant (ESSU) with stationary and / or sliding block for continuous production of cast or molten strands; Light Arc Vacuum Melting Furnace (LBV); Combination system of the types mentioned, in particular for an ESU system with stand crucible and / or sliding bar and an "Electron Beam Furnace" (EB).

The melting furnace 1 has a crucible 10, which is preferably lined cold or refractory. The crucible 10 is a bottom-closed hollow cylindrical vessel designed for melting alloying ingredients, aggregates, etc. The melting furnace 1 further has a furnace hood 20, which is designed to close the crucible 10. Preferably, the oven hood 20 is compatible for different crucible dimensions. In addition, the furnace hood 20 preferably has a cooling, such as water cooling on.

Above the furnace hood 20, a height-adjustable electrode carriage 30 for holding, rotatable bearings, rotating and method of an electrode rod 40 is provided. For this purpose, the electrode carriage 30 has an electrode receptacle 31 which rotatably supports the electrode rod 40. The electrode carriage 30 can also have a rotary drive 32 for rotating or rotating the electrode rod 40 about its axis. The rotary drive 32 may for example be attached to the electrode holder 31 or integrated with it, so that a height adjustment of the electrode carriage 30 is ensured together with the electrode rod 40 at the same time rotating electrode rod 40.

The electrode rod 40 supports a self-consumable electrode 4, also referred to as a "self-consumable electrode".

When the oven hood 20 is mounted and the electrode carriage 30 and the electrode rod 40 are mounted, the electrode bar 40 and / or the immersed Electrode 41 by a akuum- and gas-tight passage 21 in the furnace hood 20 in the crucible 10 a. The melting energy inside the crucible 10 is generated, for example, by an arc burning between the tip of the electrode 41 and the surface of the molten bath S (also referred to as "sump or" metal sump.) In order to maintain a stable arc, the distance between the electrode tip and the surface of the molten bath S are kept constant in the defined range.

For applying a melt current to the electrode 41, it is connected via power lines 51 to a power supply 50, which is preferably a high-current power supply. The power lines 51 can be realized by busbars 52 which are connected to flexible power strips or power cables 53, solely by flexible power cable 53 or otherwise, to ensure a reliable power supply despite adjustability of the electrode carriage 30. The power lines 51 are connected to contacting devices 43 of a current collector 42. The current collector 42 is part of or connected to the electrode rod 40 in order to transfer the current supplied by the power supply 50 via the contacting devices 43 to the rotatable and movable electrode rod 40. The current collector 42 may in this case be designed to be compatible for various formats of electrode rods 40. The current collector 42 may have bushings for receiving the power lines 51 and / or for protection against damage and dirt. The current collector 42, via which the current is transmitted to the electrode rod 40, is preferably water- or air-cooled.

According to the embodiment of Figure 1, a coupling 44 is provided between the electrode rod 40 and a stub 45, whereby a circuit for supplying the electrode 41 and a holder of the electrode 41 is constructed, so that between the electrode 41 and the melt, an arc in the crucible 10 is flammable or melt energy can be introduced into the melt and this can be kept constant with the height-adjustable electrode carriage 30 over the entire melting time under vacuum, protective gas or atmosphere.

In plants operating under vacuum, such as LBV or EB furnaces, the melting energy is generated by the arc burning between the tip of the electrode 41 and the surface of the molten bath S in the crucible 10. In order to maintain a stable arc, the distance between the electrode tip and the surface of the molten bath S must be kept constant. This is done via a control, not shown, which can be done, for example, computer-aided and algorithmic. In systems operating under protective gas or atmosphere, such as ESU or inert gas ESU systems, the melting energy is converted into Joule heat by the conversion of electrical energy to the resistance of the slag.

For tracking, adjustment and oscillation of the electrode rod 30, the melting furnace 1 has the above-mentioned height-adjustable electrode carriage 30 for holding the electrode rod 40. The mobility of the electrode rod 30 is in this case provided along the axial direction of the electrode rod 40, ie in the up / down direction according to FIG. 1. The electrode rod 40 is preferably adjusted according to the electrode consumption oscillating. By oscillating the electrode 41, the electrode tip is kept constant in the slag bath in a defined range, in particular the distance between the electrode tip in the slag bath and the surface thereof is kept constant. The mobility is preferably realized by a spindle drive 33, which is part of the electrode carriage 30 or rigidly connected thereto. The spindle drive 33 acts with a spindle 61 of a frame 60 together, the components of the melting furnace 1, in particular the electrode carriage 30, the furnace hood 20 and the crucible 10 carries. For example, the spindle drive 33 may have one or more motor-driven spindle nuts which engage in a thread of the spindle 61 in order to adjust the electrode carriage 30 in height by rotation of the spindle nuts.

The contacting devices 43 can be constructed in various ways, moreover consist of different conductive and non-conductive materials, as long as a secure contact with the rotatable electrode rod 40 is ensured. Thus, FIG. 2a shows a receptacle 43a into which liquid gallium 43b has been introduced. Also, into the liquid gallium is immersed a current output 43 c connected to the power supply 50 via the power lines 51. In this case, other current-carrying liquids come into consideration as liquid power transmission means. FIG. 2b shows a further exemplary structure for current transmission using brushes 43d, for example of a graphite-containing and / or copper-containing material (such as graphite, hard graphite, carbon, carbon fiber, copper, copper alloy, etc.), which is connected to a receptacle 43e the electrode rod 40 are in frictional contact. FIG. 2 c shows a further construction which, instead of the brushes 43 d, uses a shell element 43 f, which is held in a receptacle 43 g in frictional contact with the electrode rod 40. The shell element 43f may be made in one piece or in several parts and, for example, from a graphite-containing material. Furthermore, the shell element 43f can be pressed against the electrode rod 40 by means of elastic elements, such as springs, in order to ensure a secure contact.

In addition to the rotability about its own axis and vertical mobility along its own axis (corresponding to the axis of the furnace column 62 described below), the electrode rod 40 can also along or around more Axles movably mounted to improve the adjustability and thus stability during melting. Further, the current collector 42 may be adjustably arranged to be adapted to the electrode rod 40 can. For this purpose, the current collector 42 may have one or more media connections, which are supplied and controlled by appropriate control points.

In order to simplify the power supply via the current collector 42, the interaction between it and the electrode rod 40 can be modularized. Thus, the contacting means 43 may be fixed by fixing means on the current collector 42 and engage in corresponding Fixieraufnahmen on the electrode rod 40 and be included in this, as was exemplified for the embodiments of Figures 2a to 2c. In this way, the current collector 42 can be reliably connected to the electrode 41 as a consumer. The electrode rod 40 may be divided by the above-mentioned coupling 44 (or the electrode 41 may be connected to the electrode rod 40 via the coupling 44) to change the electrode 41, in particular the replacement of a spent electrode 41 with a new electrode 41, to simplify. The coupling can be hydraulically or pneumatically actuated.

The frame 60 may have a furnace column 62, on which the electrode carriage 30 and / or the furnace hood 20 are guided and held. In addition, other components, such as the spindle drive 33, can be guided and held on the furnace column 62 in order to achieve a modular construction of the melting furnace 1 in this way. Thus, the crucible 10 is also guided and held on the furnace column 62 via a furnace platform 1 1 and a stage carriage 12 according to the present embodiment. While the furnace platform 1 1 is fixed in a level crucible installation, according to the embodiment shown in FIG. 1 (sliding-plate installation), the crucible 10 is thereon Way height adjustable. For this purpose, the furnace platform 1 1 via a guide 13 and / or the stage carriage 12 may be mounted on the furnace column 62 movable. The mobility can be realized via a stage spindle drive 14, which cooperates with a stage spindle 15. For example, the stage spindle drive 14 may have one or more motor-driven spindle nuts which engage in a thread of the stage spindle 15 in order to adjust the crucible 10 in height by rotation of the spindle nuts. Thus, the crucible 10 can be lowered and / or raised in accordance with the filling rate of the crucible 10 and / or the electrode melting rate. In addition to the vertical mobility along the axis of the furnace column 62, the crucible 10 can also be movably mounted along further axes in order to improve the adjustability and thus stability during melting. For example, the adjustment along axes that are perpendicular to the axis of the furnace column 62, be realized by means that are integrated below the bottom plate of the crucible 10, such as in the furnace platform 1 1.

The vacuum-tight passage 21 of the furnace hood 20 ensures the vertical movement of the electrode rod 40 through the center of the furnace hood 20, which is attached and guided according to the present embodiment via a hood carriage 22 on the furnace column 62. The height adjustment can also be done by means of a spindle drive or as shown in Figure 1, for example by means of one or more hydraulic cylinders 23 which are mounted on one side on the hood car 22 and on the other side of the electrode carriage 40 and arranged to a Set relative distance in between.

The rotatable and vertically movable electrode rod 40 allows the end face of the electrode 41 of a conventional V-shape, cf. 3a, in a flat U-shape, cf. Figure 3b, modify. Thus, preferably, the shape of the metal sump S under the electrode 41 is also changed from the V shape to a flat U shape. Preferably, the smelting furnace 1 has one or more weighing cells (not shown in the figures) which are measuring cells for weighing the weight of the electrode 41 and / or the molten block S in the crucible 10. Preferably, the load cells are installed below the bottom plate of the crucible 10 and / or on the electrode carriage 30 and / or on the stage wagon 12, particularly preferably below the fusible link 10. In this way, the measurement accuracy can be improved in a rotating furnace 1 with rotating electrode.

Where applicable, all individual features illustrated in the embodiments may be combined and / or interchanged without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

1 melting furnace

10 crucible

1 1 oven platform

12 stage wagons

13 leadership

14 stage spindle drive

15 stage spindle

20 oven hood

21 implementation

22 hood cars

23 hydraulic cylinders

30 electrode carriage

31 Electrode recording

32 rotary drive

33 spindle drive

40 electrode rod

41 electrode

42 pantographs

43 contacting device

43a recording

43b liquid gallium

43c power delivery

43d brush

43e recording

43f shell element

43g recording

44 clutch

45 stubs power supply

power line

conductor rail

power strip

frame

spindle

Furnace pillar metal sump / molten bath

Claims

claims

1. Furnace (1), in particular for the production of metal alloys and non-ferrous alloys by melting alloy constituents, comprising a crucible (10), an electrode rod (40) with an self-consuming electrode (41) attached thereto and a power supply (50) , which is arranged to supply power to the electrode (41) via the electrode rod (40), wherein

the electrode rod (40) is rotatable about its own axis during the melting process and can be moved along its own axis.

Second melting furnace (1) according to claim 1, characterized in that it is arranged so that the electrode rod (40) is simultaneously rotatable and oscillatable during the melting process.

3. melting furnace (1) according to claim 1 or 2, characterized in that the electrode rod (40) via an electrode holder (31) on an electrode carriage (30) is fixed, which is held on a furnace column (62) and guided to the mobility.

4. melting furnace (1) according to claim 3, characterized in that the electrode carriage (30) by means of a spindle drive (33) is movable, wherein the spindle drive (33) is preferably attached to the electrode carriage (30) and having one or more motor-driven spindle nuts , which cooperate with a spindle (61) which extends substantially parallel to the furnace column (62).

Melting furnace (1) according to claim 3 or 4, characterized in that it has a motorized rotary drive (32) for rotating the electrode rod (40) about its axis, wherein the rotary drive (32) is preferably attached to the electrode holder (31).

Melting furnace (1) according to one of the preceding claims, characterized in that the electrode rod (40) is electrically connected to the power supply (50) via a current collector (42), the current collector (42) having one or more contacting means (43), configured to transfer the current supplied from the power supply (50) to the electrode rod (40).

Melting furnace (1) according to claim 6, characterized in that the contacting device (43) comprises:

a receptacle (43a) electrically connected to the electrode rod (40) and containing a conductive liquid (43b), preferably liquid gallium, into which a current output electrically connected to the power supply (50) is immersed is; and / or one or more brushes (43d), preferably of graphite-containing and / or copper-containing material, in frictional contact with the electrode rod (40); and or

a shell element (43f), preferably of a graphite-containing and / or copper-containing material, which is in frictional contact with the electrode rod (40).

Melting furnace (1) according to one of the preceding claims, characterized in that it comprises a movable furnace hood (20) which is adapted to close the crucible (10), wherein the electrode rod (40) and / or the electrode (41) by a preferably Vacuum and gas-tight passage (21) in the furnace hood (20) in the crucible (10) is immersed.

9. melting furnace (1) according to claim 3 and 8, characterized in that the furnace hood (20) is held on the furnace column (62) and guided for movability, wherein the furnace hood (20) by means of a hydraulic cylinder (23) is mounted on the electrode carriage whereby a relative distance therebetween is adjustable.

10. Melting furnace (1) according to one of the preceding claims, characterized in that the crucible (10) via a furnace platform (1 1) on a stage carriage (12) is fixed, which is held on the furnace column (62) and guided to the mobility ,

1 1. Melting furnace (1) according to claim 10, characterized in that the stage carriage (12) by means of a stage spindle drive (14) is movable, wherein the stage spindle drive (14) is preferably attached to the stage wagon (12) and one or more motor-driven spindle nuts having with a stage spindle (15), which runs substantially parallel to the furnace column (62) cooperate.

12. melting furnace (1) according to one of the preceding claims, characterized in that the melting furnace (1) has one or more weighing cells for weighing the weight of the electrode (41) and / or the crucible (10).

13. melting furnace (1) according to claim 12, characterized in that at least one of the load cells below the bottom plate of the crucible (10) is installed.

14. melting furnace (1) according to claim 12 and one of claims 3 to 5, characterized in that at least one of the weighing cells on the electrode carriage (30) is installed.

15. melting furnace (1) according to claim 12 and claim 10 or 1 1, characterized in that at least one of the load cells on the stage wagon (12) is installed.