DE2506192A1 - METHOD AND DEVICE FOR IMPRESSING A MOVEMENT ON A MOLTEN WEIGHT OF IRON - Google Patents

Description

BRITISH STEEL CORPORATION - 33 Grosvenor Place - LONDON / England

Method and device for impressing a movement on a

molten iron mass

The invention relates to a method and an apparatus with which a molten iron mass, for example steel, is moved can be impressed.

In accordance with the invention, the method of imparting motion to a molten mass of iron in an upright container is along the length of the upright container Container-.distributed to arrange a plurality of separate coils, and energizing the coils sequentially by a source of direct current, producing a unidirectional electromagnetic Field is generated along which the molten mass is propelled.

If the field is directed upwards, then it will be melted Mass, e.g. steel, is subjected to a circular motion, namely the liquid steel is guided upwards along the walls of the vessel, namely where the electromagnetic field is strongest, and the liquid steel returns through the middle part of the container back down.

509834/0270

The molten steel performs this kind of movement, even if the vessel is a continuous casting mold, such movement being particularly advantageous, as in FIG GB-PS 1,326,728. This is especially true for some or completely deoxidized steel too. Furthermore, the method according to the invention can be used, for example, to achieve thorough mixing in pans or other vessels during the manufacture of an alloy to achieve temperature and composition become homogeneous, and thus the separation of impurities, for example deoxidation products, proceeds.

The invention also relates to an apparatus for carrying out the above-mentioned method. The device device has a separate switch for each of the coils and a port switching stage closes and opens it Switches consecutively, making the coils consecutive are excited by a DC voltage source and a traveling field is generated.

In comparison with AC excited systems for imparting motion in this way, DC excitation has the advantage of increased control flexibility, i.e. the port switching pulse sequence can be changed, and it results lower energy losses, especially in connection with an electrically conductive vessel, e.g. a copper mold, where the AC losses are significant if the current is continuously changed while it has been shown to be at a certain copper shape 90 $ of that generated by direct current Magnetic flux is transmitted through the walls.

An exemplary embodiment of the invention is illustrated below described in the drawing. In the drawing show:

503834/0278

3 Fig. 1 is a circuit diagram of the device according to the invention;

Fig. 2 is a partial sectional view of a mold for continuous casting.

According to Figure 1, a DC voltage source (not shown) placed on terminals 1 and 2 and three contactors 3, 4, 5 are in series with each "a coil parallel to each other connected to the terminals.

An incremental step 9, for example in the form of a cam switch is electrical or mechanical with the contactors 3 * 4.5 connected, so that these switching contacts are consecutive, close and open, energizing the coils in the order 6, 7,8 - 6,7,8. In particular, the consequence is such that the excitation periods of neighboring switches overlap somewhat, i.e. switch 4 closes before switch 3 opens and switch 3 closes before switch 5 opens, and so on. In this way it is achieved that in none At the moment there is no electromagnetic field in any of the coils. The coils are wound so that an in unidirectional field is generated.

In a practical embodiment, the coils become tight wound adjacent to one another and aligned with one another and the coils are passed around or in the walls of the vessel in which the molten metal is to be moved embedded in these walls so that the generated electromagnetic field drives the metal in a direction determined by the direction of the field and by the order in which the coils 6,7,8 are energized successively. At a upright vessel in the shape of a mold or a pouring ladle the metal is set in a toroidal circular motion. Such an example can be seen from FIG.

503834/0278

Figure 2 shows a copper mold 10 of rectangular cross-section with water cooling, for continuous casting. The form 10 is made from a Ladle 11 is fed with molten steel. The ladle 11 has a downwardly leading pouring tube 12 with an outlet nozzle 13. Above the surface of the molten steel lies a molten slag cover 14. The side surfaces of the steel are cooled by the mold and cast Strand 15 is withdrawn from the continuous casting mold in a known manner.

The coils 6,7 * 8 are embedded coaxially one over the other in the wall of the mold and they are ^{excited separately via the supply lines 3% ^ 1} * 5 'via the three switches 3 * ^ * 5 in the manner described. Accordingly, energizing the coils 6, 7 * 8 successively causes the molten steel to rise upwards, particularly in the outer layers where the field is strongest, so that the metal is guided towards the center of the mold to wrap itself in one closed circle to move further. This circulating effect creates a negatively segregated outer surface layer, or an edge around the cast body, creating characteristics in the steel which allow subsequent treatment in that this "edge" has a lower percentage of certain elements than the central part and also in general has a greater purity as far as the non-metallic inclusions are concerned.

For example, in the special application as described in GB-PS 1 326 728, advantages in comparison with an alternating current excitation, since fewer Energy losses occur, and better control of the excitation can be achieved.

509834/0278

The invention has been described above with reference to the exemplary embodiment. However, it is clear that ' the invention is intended for other applications and numerous modifications can be made without to leave the scope of the invention. For example, thyristors or other electronic circuit elements can be used as Switch can be used. In the same way, electronic circuits can be used as an incremental stage.

Claims

509834/0278

Claims (1)

- 6 PATENT CLAIMS Method of imparting motion to a molten mass of iron contained in a Contains an upright vessel, around which windings are passed, thereby marked e i ehnet, that the coils are excited separately and successively by a DC voltage source, whereby a traveling electromagnetic field is generated in one direction, which carries the molten mass with it. Method according to claim 1, characterized in that the electromagnetic field is upward is judged. Method according to claims 1 or 2, characterized in that successive coils are so energized be that the DC voltage excitation of a coil the excitation period of the following Coil overlaps, creating a continuous field in the vessel. 4. Device for performing the method according to claims 1 to J5> characterized in that several separate coils (6,7 * 8) around the Vessel are laid around and extend along its length so that each of the coils is a separate Switch (3 * ^ * 5) is assigned to the 509834/0278 lie between the coils and a DC voltage source, and that an incremental stage (9) the switch closes one after the other and " opens, which successively energizes the coils and one running in one direction electric traveling field is generated, along which the molten mass is propelled. 5. Apparatus according to claim 4,
characterized in that the coils are embedded in the wall of the vessel. 6. Device according to claims 4 or 5 * characterized in that the coils are wound and energized so that an upward field is generated. 7. Device according to claims 4 to 6, characterized in that the step-up stage energizes the coils successively so that the period of the direct current excitation of one coil overlaps the period of DC excitation of the following coil, whereby a continuous field is achieved in the body. 8. Device according to claims 4 to 7, characterized in that that the vessel is a continuous casting, or a pan or other vessel in which the molten iron mass is to be stirred. 509834/0278 Blank page