THEORETICAL MODELING OF AN ISOKINETICAL STEEL FEEDING SYSTEM FOR NEAR-NET-SHAPE STRIP CASTING

During near-net-shape casting as considered here, liquid steel in thic knesses between 5 and 15 mm has to be put onto a cooled belt recircula ting with speeds of 30 to 60 m/min. On the belt the liquid steel solid ifies, before it can be subjected to one or two in-line hot deformatio n steps. The requirement that the surface and the shape of the strips should already have the best possible structure upon being cast means that high demands are placed above all on the liquid steel feeding sys tem. Especially the liquid metal should ideally be cast with the lowes t possible turbulence and at a casting speed which is equal to the spe ed of the conveyor belt or cooled conveyor belt. In other words, the r elative speed between the cast liquid and the cooled conveyor should b ecome ''zero'' in order that the cast liquid can be more or less ''lai d'' onto the cooled conveyor (known as isokinetic feeding). Different kinds of feeding liquid metals onto a circulating belt are reported wi th main emphasis on the theoretical modelling of the so-called underpr essure feeding systems. It is shown that, on the one hand, the casting speed can be regulated independently of the input mass flow rate into the tundish and, on the other hand, the liquid can be accumulated in the tundish or discharged from it at constant casting speed.