摘要:
A method and apparatus provide for the determination of the rate-of-rise of the level of a liquid, such as molten metal in a mold, in a reliable, accurate, and flexible manner. Molten metal passes from a container through an adjustable valve in an orifice to a mold. A microwave generator is connected to a microwave antenna located above the mold for transmitting microwaves to the surface of the molten metal in the mold. A mixer/detector is operatively connected to the antenna, and a computer is operatively connected to the mixer/detector. The computer processes the mixed signal received from the mixer/detector after it is converted to a digital signal. This digital signal is responsive to the Doppler signal caused by change in the level of the metal in the mold. The rate-of-rise of the surface of the molten metal is calculated in response to the digital signal, and is displayed on a monitor. The slide gate is controlled to adjust the amount of molten metal flowing from the container to the mold to achieve a desired rate-of-rise. The computer uses various techniques, such as calculating rolling averages and optimizing maxima-to-maxima and minima-to-minima time interval calculations, to improve reliability in the presence of noise, spurious multiple reflections, and disturbances in the molten metal surface.