Flame cutting thick steel prods., esp. continuously cast slabs - using burner underneath slab to obtain clean cut

摘要

Ferrous metal prods. of thickness >50 mm and possibly exceeding 500 mm, are cut by >=1 oxygas- or plasma-burners. The prod. is aligned so its longitudinal axis and its majore width are horizontal in the cutting zone; and cutting is effected by one or more burners located below the prod. so the gas jet or jets travel upwards. The prods. is pref. a billet or wide slab travelling out of a continuous casting plant. The burner nozzle pref. travels at a distance of 100 + 50 mm from the bottom surface of the prod. and the nozzle pref. travels at a distance of 100 plus-or-minus 50mm from the bottom surface of the prod. and the nozzle is pref. at 0-30 degrees w.r.t. a vertical line which is at 90 degrees to the bottom surface of the billet. The pref. plant includes 1 burners travelling underneath the billet. With conventional flame cutting plant using burners above the slab, solidified blobs contg. metal and slag are formed on the bottom of the cut edge; such blobs damage the rolls of rolling mills and/or are expensive to remove. The invention eliminates such defects.