| 摘要 |
PURPOSE:To confine inclusions under a box shaped jig which is provided with a hole for inserting an immersion nozzle and a hole for blowing an inert gas and to clean up a bottom slab by placing said jig on a dummy bar head and starting continuous casting. CONSTITUTION:A packing 6 is inserted between a dummy bar head 1 and a copper plate 5 of a casting mold, nail scrap 7 are thinly laid and a box type jig 10 is placed thereon, as an initial sealing operation for the casting mold. The jig 10 is formed by mounting a net-like steel plate 12 in the bottom of steel bars 14 for stanchions supporting an upper steel plate 13 having a hole 15 for blowing an inert gas and a nozzle 16 for inserting an immersion nozzle. The inert gas is blown through a pipe 11 from the port 15 to create a nonoxidative atmosphere, whereafter an immersion nozzle 9 is inserted through the hole 16 and casting is started. The dirt and inclusions in the initial period of casting are then confined between the bar 1 and the jig 10, whereby the diffusion of the dirt and inclusions to the bottom slab is prevented and the quality of the slab is improved. |
