GB1493534A - Continuous metal casting plants - Google Patents

Abstract

1493534 Continuous casting ASEA AB 26 Feb 1975 [27 Feb 1973] 7969/75 Heading B3F [Also in Division B1] In at least one roller of at least one pair of rollers 11, 11<SP>1</SP> for withdrawing the cast strand in a continuous casting plant, there is arranged an electromagnetic, multi-phase stirrer 15 or 15<SP>1</SP>, producing a field moving parallel to the longitudinal direction of the roller, to stir the molten core. There may be at least one stationary stirrer in each of a number of roller pairs 11, 11<SP>1</SP>, 12, 12<SP>1</SP> and 13, 13<SP>1</SP>, the directions of the field movements varying from one pair to another. There may also be stirrers outside the rollers. There may be a stirrer in each of the rollers of the or each pair, the direction of the fields being the same in the stirrers of the same pair to provide rotation of the melt in transverse planes. They may be opposed if the strand is of large cross-section. To ensure breaking up of dendrites, the direction of field movement should differ at different parts of the casting path, e.g. be alternately in opposite directions. The direction may vary at longer intervals than from one pair to the next. The frequency f of the stirrer is such that p/T<SP>2</SP><f<2p/T<SP>2</SP> where T is the pole pitch in metres and p the strand resistivity in ohm mm<SP>2</SP>/m., f may be 50-60 Hz. but may be as low as 2-3 Hz. for a stirrer 2 mm. in length. There may be different frequencies along the strand; e.g. a higher frequency at the beginning and lower downstream.