METHOD FOR CONTROLLING POSITION OF LANCE FOR ADDITION

摘要

PURPOSE:To control the relative positional relation between a lance and molten metal level with good accuracy by downward moving a lance insulated and connected at the front end and rear end, detecting the contact thereof with the molten metal and rising the lance at a high speed in accordance with the signal thereof. CONSTITUTION:The front end 20A and rear end 20B of the lance 20 are connected via an insulating flange 22 to constitute an integral construction. The lance 20 is lowered by a vertical driving device 30. The position of the top end 20E of the lance is detected by a pulse generator 72 and a lance position detecting circuit 74 and the result thereof is displayed on a display device 82. A molten iron detecting circuit 76 detects the molten iron surface when the end 20E contacts with the molten iron surface 15. The lance 20 is stopped by the signal thereof and the molten iron level is displayed on the device 82. The once stopped lance 20 is raised at a high speed by as much as the set height by a pole change motor 32 of the vertical driving device 30. The lance 20 is raised at a high speed by as much as the set height by the operation similar to the above-mentioned operation when the molten iron surface 15 rises and contacts the lance 20 again.