Electromagnetic stirring (EMS) suppresses the growth of columnar crystals of billets and reduces the tendency to cracking during casting and at low temperatures. A caster was used for the testing of two induction stirrers – one on the actual mould and the other beneath the mould – to determine the effect of EMS on the formation of the structure of non-alloy steel. As part of these tests, certain parts of the billets had been cast without the use of stirrers and other parts underwent alternate switching on and off of the stirrers for as many as nine combinations of modes. Samples were taken from the sections of these billets, fine-ground and etched in order to make the dendritic structure visible. The mode with the highest effi ciency was when both stirrers ran simultaneously. The growth of the columnar crystals, which pointed inward, was limited to 1/4 -to- 1/3 of the length of the case when there was no stirring. Experimental research was also confronted with results acquired from the application of the models of the temperature field and chemical heterogeneity and the physical-similarity theory. Statistical monitoring of the quality of concast billets has proven that stirring significantly reduces the occurrence of defects – in this case cracks.
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New equipment for electromagnetic processing of weak conducting material melts was numerically investigated. Significance of different effects and physical phenomena was evaluated. Complicated melt flow structure was obtained at specific equipment parameters.
PL
Nowe wyposażenie do elektromagnetycznego przetwarzania kąpieli materiałów słabo przewodzących zostało przebadane w drodze analizy numerycznej. Ważność różnych efektów i zjawisk fizycznych została oceniona. Dla konkretnych parametrów urządzenia otrzymano skomplikowana strukturę przepływu kąpieli.
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The paper deals with computer modeling of selected processes accompanying levitation melting that is controlled by electromagnetic field. Particular attention is paid to the free boundary of melt whose shape follows from the balance of all forces acting on its surface. The paper presents the mathematical and computer models of the problem and algorithm of its solution. The theoretical analysis is illustrated on a typical example whose results are discussed.
PL
W artykule przedstawiono modelowanie komputerowe wybranych procesów towarzyszących topieniu lewitacyjnemu, sterowanej polem elektromagnetycznym. Szczególną uwagę zwrócono na swobodne brzegi płynnego stopu, które kształtuje równowaga sił działających na jego powierzchni. Zademonstrowano model matematyczny i model komputerowy oraz algorytm jego rozwiązania. Analiza teoretyczna została zilustrowana typowym przykładem obliczeniowym.