SE418934B - PROCEDURE FOR REMOVING NON-SUBSTANCED PARTS IN A CASTING STRING FROM A CASTING MACHINE - Google Patents

Description

7909003-1 10 15 20 25 50 and thus a smoother solidification (smoother solidifying front). The right amount of cores gives a constant two-phase area = transition area solid-liquid phase, and no or few victories (eg white bands) arise. At two.phase food-. reduces the two-phase area in the melt with the risk of white stripes, and many. growth nuclei can increase the extent of this area. Manivill have a balance between the extent of the area and the length of the agitation.

The statement is based on. a solution to these problems, and relates to a method according to the first paragraph where the strand is formed in a mold, and the stirring is performed by means of at least one electromagnetic stirrer, suitably straight, and asymmetrical.

The method according to the invention is characterized in that the metal flow in or under (after) the mold is measured, and that the measurement signal thus obtained is used for controlling the stirring asymmetry in such a way that when a reduced metal flow is achieved the asymmetry increases and vice versa. when one is able to control the reversal so that a constant training speed is obtained, and one avoids tackling the difficult problem of measuring two-phase area width under the coil. Decreased measured flow now according to the invention gives rise to increased asymmetry, and the * tm balance as well as the flow increases, and vice versa.

The invention is further exemplified in the accompanying figures, of which Figure 1 shows stirring at slabs and Figure 2 a circuit (block diagram).

Figure 1 shows the tapping of steel or iron melt at 4 down into a downwardly open, shaped mold 3, in which the cast iron 5 is formed and subsequently solidifies, first at the surface. The invention relates to a method of stirring in the non-solidified part 6 of the string 5. Stirring can take place at slabs as well as billets and blooms, whereby in the usual way the stirrer is fed in two or three phases and with a frequency of between 0.5. and 4 Hz, preferably 1-2 Hz for slabs, at about 25 Hz for blooms and at 50-60 Hz for motorists.

The stirrer is designed for asymmetric stirring, for example with 10% higher or lower current in one phase than in another, but you can also perform the players at different speeds, to reach. same asymmetry effect. The stirrer can also be designed in such a way that the phase difference in the two-phase case deviates from 90 ° and in the three-phase case deviates from 120 °. The so-called two-phase area, ie the length of the agitation, can be varied in different ways. way by changing the degree of asymmetry, and ._. r- __ ..

Claims (4)

10 7909003-1 3 you can change in some cases. all the way to symmetrical stirring. The flow can be measured in a suitable manner, for example at 9 next to the mold 3, and this measures; This can be done by magnetic, mechanical, chemical, optical means or in another way within the framework of what is available in the art. The stirrer 7 is here located outside a support roller B, which should be made of non-magmetic material. In the flow instrument or instruments for the flow in the molten metal 9, it is arranged to output a signal to a control-regulating device 10, which in turn is arranged to be able to control the asymmetry of the stirrer 11 (see Figure 2). So you want. according to the invention maintain a constant flow in order to obtain uniform quality and the absence of vice pathways. If the flow is changed for any reason, this is indicated in the measuring instrument 9 and the asymmetry is adjusted so that the turbulence is changed and the desired flow is reset. in the case of reduced flow, for example, aeymmetry is increased and vice versa, and as mentioned, the asymmetry can be adjusted by changing phase currents or phase angles. One can also imagine the combination of phase angle and current change or that on. otherwise change the asymmetry. It is also possible to combine the asymmetric stirrer with a symmetrical stirrer in a manner known per se. The invention is further exemplified above and can be varied. in many ways within the scope of the following claims. A method of agitating non-etched portions in a casting strand from an etch-threaded chin, wherein the string 1 is a karin (5) and the agitation is performed by means of at least one electromagnetic stirrer (7), suitably straight, and asymmetrically, characterized therefrom. , that the metal flow in or under (after) the mold (3) is measured (9), and that the resulting correction signal is used to control the stirring asymmetry on. such that when a reduced metal flow measured the asymmetry is increased and vice versa. 2. A method according to claim 1, characterized in that the phase current in a phase in the inertia deviates from the current in at least one other phase, the deviation sept being controlled by means of the degree of flow. _ _ '7909003-1 lt 3. A method according to claim 1, characterized in that the electromagnetic stirrer is designed with different. winding fabric number in one phase relative to at least one other phase, whereby the current in the different phases can be varied in the event of a changed »flow signal in order to vary the degree of asymmetry. 4. A method according to claim 1, characterized in that the stirrer is fed 2- or ä-phaseb, wherein the phase angle difference, which in symmetrical feeding is 90 ° and 1200, respectively, is changed in order to achieve asymmetry, the phase angle being further changed in the event of a changed flow signal. purpose to achieve degree of asymmetry.