DE1458942C

DE1458942C -

Info

Publication number: DE1458942C
Authority: DE

Description

Die Erfindung bezieht sich auf eine Anordnung zur Erzeugung einer Badbewegung in Metallschmelzen.The invention relates to an arrangement for generating bath movement in molten metal.

Elektrische Öfen, etwa in Gestalt von Lichtbogenöfen, sind seit langem bekannt und beispielsweise in den deutschen Patentschriften 131414, 256 072 und 541333 beschrieben. Grundsätzlich unterscheidet man bei den Elektroofen solche, bei denen die Elektroden außerhalb der Schmelze verbleiben und zwischen den einzelnen Elektroden oder zwischen den Elektroden und der Schmelze ein Lichtbogen ausgebildet wird, und solche, bei denen die Elektroden in die Schmelze eintauchen. Häufig wird eine Elektrode von der Auskleidung des Ofens gebildet, während die übrigen Elektroden von oben her an das Schmelzgut herangeführt sind. Zumindest diese letzteren bestehen in der Regel aus Preßkohle oder aber auch aus Metall. Ebenso häufig sind auch einzelne Kohleoder Metallelektroden als Bodenelektroden in die Auskleidung des Ofens eingesetzt.Electric furnaces, for example in the form of electric arc furnaces, have long been known and, for example, in German patents 131414, 256 072 and 541333 described. A basic distinction is made between electric ovens and those with electrodes Remain outside the melt and between the individual electrodes or between the Electrodes and the melt an arc is formed, and those in which the electrodes are in immerse the melt. Often times, an electrode is formed by the lining of the furnace while the remaining electrodes are brought up to the melting material from above. At least the latter exist usually made of compressed coal or made of metal. Just as common are individual coal or Metal electrodes used as bottom electrodes in the lining of the furnace.

Es ist bekannt, solche elektrische öfen mit Rührwerken auszustatten, die bei dem im Ofen stattfindenden Vorgang folgende Vorteile ergeben:It is known to have such electric ovens with agitators to equip, which give the following advantages in the process taking place in the oven:

1. Beschleunigter chemischer Reaktionsablauf;
- 2. erhöhte Gleichförmigkeit der Temperatur in der Schmelze;1. Accelerated chemical reaction process;
- 2. increased uniformity of temperature in the melt;

3. erhöhte Gleichförmigkeit der Schmelze selbst und3. increased uniformity of the melt itself and

4. verbesserte Entschlackung.4. Improved purification.

Insbesondere bei großen elektrischen Lichtbogenöfen und bei solchen zur Erschmelzung von hochwertigen legierten Stählen spielt ein solches Rührgerät eine äußerst wichtige Rolle. Daher wurde eine Anzahl von Verfahren zum Rühren geschmolzener Metalle in elektrischen Lichtbogenöfen vorgeschlagen, von denen sich jedoch nur zwei Arten bewährt haben, nämlich solche, die zur Erzeugung einer Rührbewegung in der Schmelze ein magnetisches Drehfeld benutzen, und solche, bei denen zu diesem Zweck ein umlaufender Gleichstrom-Elektromagnet Verwendung findet. Bei herkömmlichen, mit solchen Rührwerken ausgestatteten Lichtbogenöfen wird das in den Ofen eingeführte Material mit Hilfe von Wechselstrom geschmolzen, der jedoch nicht für das Rühren des geschmolzenen Metalls ausgenutzt wird, da es bisher üblich war, zum Rühren der Schmelze lediglich die Kräfte zu verwenden, die durch ein auf die Schmelze einwirkendes, relativ veränderliches Magnetfeld in dieser durch Wirbelströme hervorgerufen werden. Infolgedessen ist die Stärke der Rührkraft bei den herkömmlichen Rührwerken praktisch ausschließlich von der Intensität des Magnetfeldes und damit von derjenigen des dieses erregenden Stromes abhängig, woraus sich ergibt, daß ein sehr starker Elektromagnet zum wirksamen Rühren der Schmelze erforderlich ist.Especially with large electric arc furnaces and those for melting high-quality ones In alloyed steels, such a stirrer plays an extremely important role. Hence, a Number of methods proposed for stirring molten metals in electric arc furnaces of which, however, only two types have proven effective, namely those that generate a stirring movement Use a rotating magnetic field in the melt, and those with which for this purpose a rotating direct current electromagnet is used. With conventional ones, with such Arc furnaces equipped with agitators are used to control the material fed into the furnace Alternating current melted, but not used for stirring the molten metal, since it has hitherto been customary to use only the forces to stir the melt, which are caused by a the melt acting, relatively variable magnetic field in this caused by eddy currents will. As a result, the strength of the agitation force in the conventional agitators is practical solely on the intensity of the magnetic field and thus that of the one that excites it Current dependent, from which it follows that a very strong electromagnet for effective stirring the melt is required.

Die Aufgabe der Erfindung besteht nun darin, eine neuartige Anordnung zur Erzeugung einer solchen Badbewegung in Metallschmelzen anzugeben, die intensivere Rührkräfte ergibt als die herkömmlichen Rührwerke, ohne daß dazu derartig starke Elektromagnete verwendet werden müssen, wie sie bei den herkömmlichen Rührwerken erforderlich sind.The object of the invention is now to provide a novel arrangement for producing such a Indicate bath movement in molten metal, which results in more intensive stirring forces than conventional ones Agitators without the need to use such strong electromagnets as in the conventional agitators are required.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß an einem an sich bekannten mit Gleichstrom betriebenen Elektroofen mit einer oder mehreren Elektroden und einer oder mehreren Bodeneleklrodcn ein oder mehrere Gleichstrom-Elektromagnete angeordnet sind, deren Kraftlinien sich mit denen des elektrischen. Feldes des Lichtbogens schneiden.This object is achieved according to the invention in that a known per se with direct current operated electric furnace with one or more electrodes and one or more floor electrodes one or more direct current electromagnets are arranged, whose lines of force are with those of the electric. Cut the field of the arc.

Die Arbeitsweise der erfindungsgemäßen'. Anordnung beruht auf der Ausnutzung der Flemingschen Linke-Hand-Regel und weicht aus diesem Grunde vollkommen von derjenigen der herkömmlichen Rührwerke unter Verwendung umlaufender magnetischer Felder ab. Erfindungsgemäß werden diejenigenThe operation of the 'according to the invention. arrangement is based on the exploitation of Fleming's left-hand rule and deviates for this reason entirely different from that of conventional agitators using rotating magnetic ones Fields. According to the invention are those

ίο Kräfte zu Rührzwecken ausgenutzt, die unter dem Einfluß eines Magnetfeldes auf einen elektrischen Leiter hervorgerufen werden, den ja die vom Schmelzstrom durchfiossene Schmelze darstellt. Demgemäß findet erfindungsgemäß ein Gleichstrom-Magnetfeld in Verbindung mit einem Gleichstromdurchfluß.durch die Schmelze Verwendung.ίο forces used for stirring purposes that are under the Influence of a magnetic field on an electrical conductor caused by the melting current represents through-flow melt. Accordingly, according to the present invention, there is a direct current magnetic field in connection with a direct current flow through the melt use.

Genauer gesagt werden erfindungsgemäß die Schmelzelektroden des Ofens mit Gleichstrom beliebiger Polarität gespeist, und in der Schmelze wird ein Gleichstrom-Magnetfeld hervorgerufen, dessen Kraftlinien zumindest in einem Teil der Schmelze den Stromverlauf der von den Elektroden ausgehenden Schmelzströme schneiden und so verlaufen, daß durch sie in der Schmelze nach der Flemingschen Regel Kräfte hervorgerufen werden, die in der Schmelze eine Drehbewegung herbeiführen. Somit wird das geschmolzene Metall in dem Ofen durch die mechanischen Kräfte gerührt, die durch die gegenseitige Beeinflussung der auch zum Schmelzen dienenden Ströme und des von dem Gleichstrom-Elektromagnet hervorgerufenen Magnetfeldes erzeugt werden. Die Größe dieser mechanischen Kräfte ist proportional dem Produkt der Stärke des durch das geschmolzene Metall geleiteten Stromes und der Intensität des Magnetfeldes, so daß eine wesentlich geringere Magnetfeldintensität für das Rühren des geschmolzenen Metalls ausreicht, als bei herkömmlichen Verfahren. Hierdurch wiederum ist es möglich, beträchtliche Einsparungen bezüglich der Kosten der Elektromagnete und ihres Stromverbrauches zu erzielen. More specifically, according to the present invention, the melting electrodes of the direct current furnace become arbitrary Polarity fed, and a direct current magnetic field is created in the melt, its Lines of force, at least in part of the melt, determine the current flow from the electrodes Cut melt streams and run in such a way that through them in the melt according to Fleming's As a rule, forces are generated which cause a rotary movement in the melt. Therewith the molten metal in the furnace is stirred by the mechanical forces created by the mutual Influence of the currents also used for melting and that of the direct current electromagnet induced magnetic field are generated. The magnitude of these mechanical forces is proportional the product of the strength of the current passed through the molten metal and the Intensity of the magnetic field, so that a much lower magnetic field intensity for stirring the molten metal is sufficient than with conventional methods. This in turn makes it possible to achieve significant savings in the cost of the electromagnets and their power consumption.

Die Einbaukosten für das erfindungsgemäße Rührwerk liegen zwar etwas höher — ungefähr um 12% — als diejenigen für die billigste Art herkömmlicher Induktionsrührwerke, welche umlaufende Gleichstrom-Elektromagnete verwenden. Wenn aber die Kosten für die Elektromagnete beider Rührwerke verglichen werden, ergibt sich, daß mehr als 60% der Erstellungskosten für das erfindungsgemäße Rührwerk auf die Bereitstellung einer Gleichstromquelle entfallen und daß die Kosten für den Elektromagnet selbst ungefähr der Hälfte der Kosten des Elektromagnetes eines herkömmlichen Rührwerkes betragen. Wenn nun aber zwei öfen mit erfindungsgemäßen Rührwerken unter Verwendung einer gemeinsamen Gleichstromquelle versehen werden, sind die Erstellungskosten für diese beiden Rührwerke um etwa 13 % niedriger als die Kosten für zwei entsprechende herkömmliche Rührwerke mit umlaufenden Gleichstrom-Elektromagneten.The installation costs for the agitator according to the invention are somewhat higher - around 12% - than those for the cheapest type of conventional induction agitators, which are rotating direct current electromagnets use. But if the costs for the electromagnets of both agitators are compared, it turns out that more than 60% the production costs for the agitator according to the invention on the provision of a direct current source omitted and that the cost of the electromagnet itself is about half the cost of the Electromagnet of a conventional agitator amount. But if two ovens with the invention Agitators using a common direct current source are provided the production costs for these two agitators are around 13% lower than the costs for two corresponding ones conventional agitators with rotating direct current electromagnets.

Die erfindungsgemäße Anordnung kann mancherlei Ausgestaltungen erfahren, von denen einige nachfolgend noch im einzelnen beschrieben sind.The arrangement according to the invention can take various forms, some of which are given below are still described in detail.

In jedem Falle kann die Bewegungsrichtung des geschmolzenen Metalls leicht dadurch umgekehrt werden, daß die Polarität entweder des durch die Schmelze hindurchtretenden Gleichstromes oder aber des Erregerstromes für den Elektromagnet umgekehrtIn either case, this can easily reverse the direction of movement of the molten metal that the polarity either of the direct current passing through the melt or else of the excitation current for the electromagnet is reversed

Claims

5 65 6

lity on the outer wall T ■ of the furnace 6 a central pole of the same and 7 an outer one are brought and. Another magnetic pole 6, the wall of which is made of magnetizable material, such as the polarity opposite to that of the poles 6 ', sheet iron, which in turn serves as the outer pole of the Elektrojttach as before. in the bottom center of the furnace arranged magnets is used. The base plate 8 of the furnace is made of non-magnetic metal, while three base electrodes 3 'are made directly from 5. The magnetic pole 6 is provided below an electrode 2 '. opposite the plate electrode 3 α on the furnace floor Each of the magnetic poles 6 ' is arranged within a radial and opposite the base plate 8 by means of an iso-plane, which runs through the central axis of the lation 14, electrically isolated, as well as the plate furnace and in which also in each case one electrode is located on the other hand through an insulation 13 against the pair of electrodes 2 ', 3'. In this case io should be insulated over the wall 7 of the furnace. The wall T. Of the furnace, made of non-magnetic plate electrode, should have sufficient removal of material from the melt into the refractory material

Also in this design, the number of embedded is to make it melt in the absence To prevent electrodes and electromagnets or magnetic poles from additional water cooling, on the wall 7 'is not necessarily limited to three. 15 Still, it will be preferable to use the Plattenelek rather can one, two or more than three electrodes as well as the magnetic pole 6 with water cool electrodes, bottom electrodes and / or electromagnets.

Find use, provided that the stirring effect of the inventive contexts to prove between the electric by the order were by Melt flowing direct currents and the magnetic 20 melts of carbon steel with 0.6% coal tables Lines of force can be achieved which show the prepreg in a 50 kg electric furnace as shown in FIG discussed same. kind of tests carried out, the

If the melt belonging to the magnetic poles 6 and 6 'was added 4% tungsten. Windings were excited, so the cores located therein are measured with the time required for homogenizing the molten metal with the time required from FIGS. 3 and 4. For comparison purposes, rity magnetized to produce three sets of magnetic measurements were made in the preparation of a similar lines of force, the mixture borrowed from each magnetic pole 6 'using a conventional oven borrowed in the center of the oven floor without agitator. The frostbite, which results in three spaces between each, is shown in FIG. 9, in which the curve A of the pair of electrodes 2 ', 3' pass through. Since the current 30 represents the values using the density of the structure flowing through the molten metal according to the invention and the curve B those obtained with direct current in the three spaces between the conventional furnace.
Pairs of electrodes is higher than in other areas. In the experiment, the tungsten in aluminum

of the furnace, it turns out that the packed in the molten niumfolien and in the central area of the Metal there generated mechanical forces greater than 35 thrown melt after the temperature is thrown and the stirring effect is thereby improved. had reached the same 1600 ° C. Samples for the

F i g. 6 shows a circuit diagram for a light-mixing analysis were at a certain point arc furnace with one of the previously described stirrer arrangements of the melt at regular intervals, with 9 sucking in a rectifier. In the experiment, a direct current for the generation of direct currents for the melting 40 current melting current of 2000 A and an exciter of the metal was designated and the bottom electrodes 3 'current for the electromagnet of 80 A, are connected to a plate electrode 3, which in the Circulation speed of the slag top furnace bottom is arranged. 10 is a switch, the area 40 to 50 cm / sec. fraud,
it allows, except for direct currents for the actual From Fig. 9 it follows that the to achieve

Melting operation in the conventional manner alternating time flows required for the uniformity of the melt to be selected, while in this case only the stirring process according to the invention using the stirrer according to the invention with a direct current arrangement is considerably reduced,
flow occurs through the melt. The exciter above was the arrangement according to the invention

Winding 5 of the electromagnet is only connected to a voltage via a Rectifier 11 fed, however, it is also possible to describe 50 electric arc furnace, however, is located to supply them via the rectifier 9 with power. It is obvious that the principle used here The polarity of the excitation current in the winding 5 not only with such, but also with others can from time to time with the help of a changeover switch 12 types of direct current melting furnace, however can be reversed in order to increase the stirring effect when used in vessels such as pouring ladles given way to increase. 55 can find.

7 and 8 show in a vertical direction
Section or a horizontal section according to the line

AA ' in the latter the construction of a practical to patent claims:

Application coming, according to the invention equipped electric arc furnace. 1, the linings 2 designates 60: 1. An arrangement for generating a Badbewedung, the electrode 3a is a reasonable in Öfenboden supply into metal melts, characterized labeled in disposed plate electrode made of bronze and 3b, the lines, that one of a per se known floor electrodes made Number of flux with direct current operated electric furnace with a steel rod, which is attached to the plate electrode or several electrodes (2, 2 ') and one or 3 a in three groups and in the refractory 65 several bottom electrodes (3, 3') one or meh material are embedded on the furnace floor in such a way that only rere direct current electromagnets (5, 6, 6 ') protrude into the melt 4 in their uppermost areas. are arranged, whose lines of force intersect with those of the 5 denoted the excitation winding of the electromagnet, electrical field of the arc.

3 43 4

becomes, whereby through the inversion vortices emerge. It is also possible to have a sufficient

called and the stirring effect thus still considerably stirring effect with only a single electrode in

is improved. the furnace center to achieve that with a variety of

More details can be found in the following ground electrodes, which in turn work together

Description of the embodiment shown in the figures embedded in the furnace floor along a circle

examples. through the center of which the vertical project

F i g. 1 shows a section through an invention of the named electrode. Will the

i equipped according to the arc furnace with a polarity of the electrodes described above

j its lower part located electromagnet; reverses, the direction of the reverses with it

! F i g. 2 shows a section through the same furnace 10 thus achieved stirring movement, the size of which in

I in a horizontal plane; remaining remains the same as long as the magnetic field is not

i F i g. 3 shows a section through an arc.

oven with another embodiment of the invention. The stirring effect comes from feeding according to the arrangement; Direct current in the excitation winding of the electric: Fig. 4 shows a section through this furnace in 15 magnets being made while at the same time direct current of a horizontal plane; is passed through the molten metal. F i g. 5 is a perspective view from which, by immersing the electrodes in the slag, the individual components of movement of the molten or molten metal or else through 1 zen metal in a furnace of the type shown in FIGS. Figures 1 and 2 show an elevated arrangement of the electrodes of the type shown; 20 space opposite the melt, the F i g. 6, a circuit diagram of the stirring action according to the invention is hardly influenced. Also results in the arrangement; Turn of solenoids without iron core in place of F i g. Fig. 7 shows a section through a practical of electromagnets in the lower part of the furnace in the execution of an equipped according to the invention essentially the same stirring effect.
' Light furnace; 25 Are three electrodes 2 and a magnetic pole 6 ge-F i g. 8 shows a horizontal section through this dimension F i g. 2, an electric furnace flows and current flows from each electrode to two adjacent F i g. 9 is a graphic representation in which bottom electrodes, as indicated by the solid arrows, the stirring action of the arrangement according to the invention. The 3 ° electromagnet arranged in the furnace floor opposite that of a conventional agitator generates magnetic lines of force that are superimposed. from the magnetic pole 6 radially outwards to the outer-der in FIGS. Arc shown 1 and 2 ren wall 7 extend, wherein it has the oven through the overall ^1, a wall 1, three pass in the lid reasonable molten metal 4 as the arranged electrodes 2, which in general, the dashed lines in F i G. 2 show. Here, anodes intersect, and three in the lower part of FIG. 35 are the electrical bottom electrodes 3, which are embedded with the magnetic power furnace wall. 4 is lines, for example at points a, b, c, d, e, and /, the molten metal, 5 an excitation winding for so that in the molten metal according to FIG. 6 the electromagnet, 6 a pole of the same, which is based on Fleming's rule, generates mechanical forces in the middle of the projection of those in the middle of the furnace. In the arrangement shown, for example, electrodes 2 and 3 are located, 7 a molten one located at the point α at 4 °

■ Furnace enclosing wall, which in this metal by one of the mechanical j Trap is made of magnetizable material and the forces are at an angle to the vertical upwards

■ represents the second pole of the electromagnet. 3 is a promoted, the electric of the inclination and 'in the furnace built base plate made of non- magnetic lines of magnetic force at the point a off

tisable material around the winding 5 of the electric 45 depends. In this way, the metal experiences in his

to shield magnets. Entire movement as shown in FIG. 5 her-

I The arrangements of the electrodes and magne- proceed, with upward movements at the points a,

i table poles, which are decisive for the movement of the c and e, downward movements on the remaining three

■ molten metal can be seen more clearly from points b, d and /. As a result, will! F i g. 2 emerges. The furnace shown is equipped with three electrodes, all of the molten electrodes in the furnace, and three bottom electrodes that cause metal to be arranged along concentric circles in the interior of the furnace and clockwise as indicated by arrow A in F i G. 5-: vertical projections alternately draw the corners of one to revolve. By reversing either ' form a hexagon, in the middle of which the magnetic current of the melting current or the excitation current for the ^; pin 6 is located. Meanwhile, the arrangement of the poles 55 electromagnet is also the direction of the orbital! not limited to the one shown here. For example, movement of the molten metal reversible,! You can also use three electrodes directly over three whereby at three points in the melt each. be-I floor electrodes may be arranged, or in the vicinity considerable eddies are generated, which considerably increase the agitation of a circle, the effect of the vertical projections.

three electrodes, a plurality of 60 instead of a single electromagnet or

: Bottom electrodes must be embedded in the furnace bottom. Solenoids on the furnace bottom can also be a variety

¹ Furthermore, the number of electrodes does not need to be provided in order to achieve a formation of the

to be limited to three, as can also be achieved with two or a magnetic field that of that of the

more than three such electrodes produce an effective single electromagnet similar to a magnetic field

i can achieve stirring work. However, it is always necessary and has essentially the same stirring effect

borrowed, which causes bottom electrodes on the furnace bottom nearby.

^; a circle to be provided which is defined by the vertical lines in FIGS. 3 and 4 is an embodiment

Projections of the electrodes arranged above are shown, in which three magnetic poles 6 'with the same pole

i 458

2. Arrangement according to claim 1, characterized in that the middle of the projections electrodes (2, 3) provided in the middle of the furnace, a magnetic pole (6) near the furnace bottom arranged and the second pole through a wall (7) surrounding the furnace made of magnetizable Material is formed.

3. Arrangement according to claim 2, characterized in that the magnet winding (5), the Surrounding the magnet pole (6) located in the middle of the furnace, inside the wall (7) made of magnetizable Material is arranged.

4. Arrangement according to claim 1, characterized in that the middle of the projections electrodes (2 ', 3 ^ a magnetic pole (6) near the furnace floor

is arranged and around the non-magnetic furnace wall (T) several radially directed magnetic poles (6 ^ of the other polarity are arranged.

5. Arrangement according to claim 4, characterized in that the electrodes (2 ^ equiaxed with the associated bottom electrodes (3 *) and are arranged within radial planes passing through the central axis of the furnace as well as the radially directed magnetic poles (6 ') are determined.

6. Arrangement according to one of the preceding claims, characterized in that a changeover switch (12) for reversing the current direction is provided in the supply circuit of the electrodes (2, 3; 2 ', 3') or the electromagnets (5, 6, 6 ') is.

For this purpose 2 sheets of drawings 909 539 / 5Λ