DE2505533A1 - CONTINUOUS CASTING PLANT - Google Patents

Description

Patent attorneys

Dipf.-lng. Helmut MissHng 63 Giessen 8, "U. 1975

Dipf.-tng. Richard Sch tee Bismarckstrasse 43

Doing. Joachim Boecker ^{Telephone: mm 7tcm}

Boe / Prs 12,340

Allmänna Svenska Elektriska Aktiebolaget Vast er as / Sweden

Continuous caster

The invention relates to a continuous caster with one or more pairs of owls for pushing out the semolina strand.

In continuous casting plants, "for example in the production of wire or rod products with a square, right-angled or round cross-section, the casting is pushed out of a ladle or a ladle furnace by means of one or more pairs of bolts that transform the casting into an arrangement, for example a rolling mill ο for the purpose of further treatment The solidification begins there on the surface and gradually spreads towards the center of the cast Center of the casting. This is due to the fact that the molten metal is "pinched off" at certain points during the solidification process. If such a constricted melt solidifies, cavities are formed in the usual way, which can be avoided by preventing the constriction. lian suggested the non-solidified rope of the cast

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with Umrührern, which are arranged along the cast strand, uinzurühren, and one iIAT this Omrührer mounted so that the electromagnetic traveling field gets a propagation direction which is perpendicular to the casting direction. If the casting direction is vertical, the traveling field has a horizontal direction.

Such an arrangement is known from the German Auslegerschrift 1 962 341, in which continuous casting is shown in a cooled Eokille, where several pairs of bolts transport the cast strand for the purpose of further treatment, the non-solidified part of the cast strand by means of a low-frequency electromagnetic stirrer with a perpendicular to the casting direction moving moving field is stirred. These agitators are in the pouring direction between the. Rolls arranged.

fen also has. Consideration made at what stage The stirring should start after solidification. It starts to at an early stage, the constrictions described at the beginning can occur, and the above-mentioned publication suggests that start stirring at a relatively late stage of solidification. One reason for this stirring is the appearance of dendritic structures in the solidified cast as well as the above-mentioned formation of cavities.

However, it has been shown that such stirring takes place both early and later during the course of solidification must, i.e. a shorter and longer distance from the casting

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pan removed, and there is a problem that the existing There is no space for such a stirrer to be placed along the casting strand allows.

The present invention has for its object to be a To develop a continuous caster of the type mentioned at the outset, in which the space problem just explained is solved.

To solve this problem, a continuous caster is after The preamble of claim 1 proposed according to the invention has the features mentioned in the characterizing part of claim 1.

Advantageous refinements and further developments of the invention are mentioned in the subclaims.

The invention creates a previously "dead" space for accommodation the agitator used. Because they are housed within the rollers, the agitators can also be stranded as close to the casting line arrange that a sufficient penetration depth of the stirring forces can be achieved. The moving field with the normally right-angled cross-sections is given a Direction perpendicular to the casting direction.

In a preferred embodiment of the invention, the Moving fields of successive pairs of rollers in different directions, which means that the dendrites that may move during the

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Form solidification, are destroyed by means of the agitation during the solidification process, which will not be the case with certainty would, if one had the same traveling field direction for successive pairs of rollers · One can "the traveling field direction Of course, you can also change at greater intervals than from one Eolle to another, but it is advisable, in principle, for different ones Provide parts of the pouring path in a different traveling field direction.

The arrangement of the agitators in the bolls also gives the possibility of having a large number of agitators on the cast strand to use. In another embodiment of the invention, you give the traveling fields in the agitators to the same Pair of rollers belong to the same direction. That way will

the
avoided that / agitation forces of two agitators cancel each other out, which would be the pail with relatively small dimensions of the cast strand.

If, on the other hand, the distance between the rollers is greater, then in certain cases one can also have opposite directions of agitation, which is explained in more detail below.

On the basis of the exemplary embodiment shown in the figures the invention is to be explained in more detail. Show it:

Fig. 1 shows the cast strand in cross section with feed rollers and agitators,

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FIG. 2 shows a section along the line A-A in FIG Fig. 1.

A strand of sieve is pushed down from a pouring ladle, not shown, by means of a number of pairs of rollers 11 and 11 * _t 12 and 12% 13 and 13 *. These pairs of rollers are hollow. and in them are static stirrer with Umrührspulen 14 »14 * (see} arranged _t * sitting on conventional laminated cores 15 and 15 * The roller pairs slide in the figure, the rolling vertically downward. Bie feed direction can" during roll pair 11 ', 11 * however "be arbitrary _t, for example completely or partially horizontal," curved or the like .. One uses thus ä & n space within _{the roller pairs 11-13 t} 11 ^r -13 * and can thereby the agitators at -many places along the solidification path, and relatively Arrange close to the casting strand, so that the non-solidified areas can be stirred in the manner shown in Fig. 2 by arrow 16. "t and 2 denote the power supplies to the various phases for the multiphase stirrer _t and the traveling field thus runs ,, whereby a horizontal agitation will be drawn according to the arrow 16 in FIG. 2, "Ber second stirrer of the same pair is fed in the same quietly ^ when nan wishes for this the same Umrührrichtung _t. od but opposite in the other case, Bas traveling field extends as _t ge says "in the case of Fig * 1 horizontal" generally should _t words, the direction of the traveling field perpendicular to the casting direction. In Fig. 2 the course of the stirring force of one stirrer is shown. It goes without saying that one _t when both

Stirrers are fed with electricity, a more complicated conversion Rührsehema receives “In principle, however, it is true that with the same Moving wave direction an interaction between the stirring forces takes place, while with opposing stirring forces with a weak, sweet cross-section, a certain mutual Cancellation of Umrüferkraft occurs, which is not desired. In the case of larger cast cross-sections, on the other hand, opposite ones can very well be used Overriding directions should be attached to a suitable Mixing scheme too. obtain.

The! Frequency of the current with which the agitators are fed, can be 50 - 60 Hz, for example «If you can't

within
solidified metal 3öncöaa »nö! No thick solidified outer layer - stir: if you want to homogenize, you have to feed with as low a frequency as possible, for example with 2 - 3 Hz with a length of the stirrer of 2 m. according to the Yerlauf solidification different frequencies for the stirrer to use, for example, a higher rate at the beginning and a lower frequency more towards the end of Sießweges "the frequency in the melt according to the equation · <TF \. - -r selected, where C- is the pole pitch of the stirrer in m and T is the specific resistance of the strand in ohms mm / m . '

In the case of continuous casting machines of the kind dealt with here, the hot and fetishized atmosphere causes difficulties. Wan recognizes the advantage achieved in this regard, which lies in the fact that

the agitators are arranged within the rollers., where they are protected against damage, such as heat damage or short circuits, as can be seen from the Mg, 1, the pairs of rollers sit relatively close to the casting strand along, and the advantage of utilizing the space within these pairs of rollers is thus evident. Of course it is also possible to accommodate agitators only in part of the roller pairs, while the other pairs of rollers on the cast strand only act mechanically

Appropriately, the traveling field direction changes from pair of rollers to a pair of rollers, for example a traveling field direction in FIG. 1 for the pair 11-11 * into the plane of the drawing can and opposite at 12-12 », while one at the pair 13-13 * selects the traveling field direction again, as for the couple 11-11 * · If one chooses the same for both converters in the same pair Moving field direction, one obtains an interaction of the stirring forces, to move the melt around in a mainly horizontal plane.

The type of static agitator can be different, but it must always be a static agitator

The system according to the invention described with reference to the figures can be used in many ways within the scope of the inventive concept disclosed Way can be varied.

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Claims (5)

- ο - claims: 1. Continuous caster with one or more pairs of rollers for ejecting the casting strand, characterized in that in all or some of the rollers (11-13 »11 ^f -13 *) multi-phase electromagnetic, static agitators are arranged, which have a substantially parallel to the longitudinal direction of the Generate a rolling traveling field. 2. Plant according to claim 1, characterized in that the traveling fields of the agitators of successive pairs of rollers have changing direction. 3 · Plant according to claim 1 or 2, characterized in that the traveling fields in the agitators of the same pair of rollers are the same Have direction. 4. Plant according to one of claims 1-3 »characterized in that the frequency in the melt according to the equation * r ^" ^ x- y 2 5 - 'k r ^ - TT ^ is chosen, where υ is the pole pitch of the stirrer ¹ 7 2 in m and S the specific resistance of the strand in ohms mm / m 5. Installation according to claim 4, characterized in that the frequency is selected to be low, preferably of the order of magnitude 2 - 3 Hz with a length of the agitator of approx. 2 m. 509835/0646