摘要 |
PURPOSE:To maintain the specified pressurizing force of a molten metal, to stabilize production and to improve the quality of a product by controlling the position of a molten metal level to always the specified range in accordance with the position of the molten metal level detected by the molten metal level detection sensor utilizing the reflected wave of the ultrasonic wave. CONSTITUTION:The molten metal 2 in a holding furnace 1 is raised in a stalk 7 or sub-riser 10 by the air pressure introduced into the furnace through a variable valve 14 by the signal of a sequencer 13. The position of the molten metal level 2b is detected by a sensor 11b for detecting the lower limit molten metal level utilizing the reflected wave of the ultrasonic wave and the pressurization is stopped. The pressure for the pressurization is decreased until a sensor 11a for detecting the upper limit molten metal level turns off when the sensor 11a detects the molten metal level 2b. The molten metal level is maintained always in the specified method and the quality is stabilized by the above-mentioned method.
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