US 4,132,259 A · Automatic control of the level of a molten metal bath

Abstract

In the continuous casting of metals by means of a water-cooled tubular mold into which the molten metal is fed by means of a refractory pouring nozzle which opens in the molten metal bath below a supernatant protective layer of fusible slag, automatic control of the molten bath level is obtained by forming an image of the upper portion of the mold with the pouring nozzle and the slag layer by means of an optical instrument, by disposing a plurality of photo-electric cells on this image along a line substantially coincident with the axis of the nozzle on the said image, some of said cells being on the image of said nozzle and others on the image of the slag layer, by determining the radiation gradient between the successive cells along said line, by taking as the analog of the level of the molten metal bath within the mold the zone of said line where said gradient reverses and by deducing a controlling signal from the position of said zone along said line. The successive cells may be connected two by two to comparators which emit an output in correspondence with the sign of the difference between the responses of the cells of each pair, these outputs being totalized algebraically to deduce the controlling signal.

Claims9

Dependent claims

In a method for the automatic control of the level of a molten metal bath to maintain same at a proper height in continuous casting molds which are fed by an elongated refractory pouring nozzle having an axis which extends downwardly into the bath below a supernatant protective slag layer extending radially from the nozzle, an optical image of the upper portion of the said mold including the nozzle and the slag layer being formed at a location spaced from the mold and being directed onto temperature measuring means to obtain analogs varying in accordance with the position of the said level within the mold, the improvement comprising the steps of:

measuring the temperatures at points disposed sequentially in spaced relationship in a line substantially lying along the axis of the image of said nozzle and along a radius of the slag layer image, in such manner that some of the temperatures are analog signals representing radiation at successive points along the periphery of said nozzle and others of the temperatures are analog signals representing radiation at successive points along the surface of said slag layer;
comparing successive analog signals to determine temperature gradients wherein the direction of the gradients reverses at a zone where said line crosses the intersection of said images of the nozzle and the slag layer;
selecting as the analog of the position of said level the zone of said line where said gradient reverses;
and generating a controlling signal based on the position of said zone along said line.

1 more element

An apparatus to generate a controlling signal adapted to achieve automatic control of a molten metal bath level within a continuous casting mold having an upper end into which the molten metal is fed through a refractory axially-elongated pouring nozzle which extends into said mold below a protective supernatant slag layer, and the mold having a lower end through which a solidified bar of the metal is withdrawn, said apparatus comprising:

an optical instrument disposed above said mold and offset laterally with respect thereto with its axis at an angle to the vertical, the instrument being operative to form an optical image of the upper end of said mold including said pouring nozzle and said slag layer;
a plurality of photo-electric cells disposed in a line lying substantially along the axis of the image of said nozzle, some of said cells intercepting the image of said nozzle and others of the cells intercepting the image of said layer;
means connected to the cells for receiving analog signals from said cells proportional to the intensity of radiation to each cell, said means being operative for determining from said signals the direction of the gradient of said analog signals along said line;
means connected to said receiving means to detect a zone along said line where said gradient reverses;
and means connected to said detect means to generate said controlling signal in response to the position of said zone along said line.

2 more elements

Dependencies are inferred from the claim text.

Automatic control of the level of a molten metal bath

Life of this patent

Automatic control of the level of a molten metal bath

Life of this patent

Abstract

Claims9