Flow cut-off method and apparatus for foundry installations

A control system for a casting installation comprising a casting ladle containing molten metal for filling a mold;

• at least one mold having an inner cavity and a sprue cup thereon, said mold being filled by a stream of metal which falls from said casting ladle into said sprue cup, thus forming in said sprue cup an accumulation of metal with a free surface while flowing from said sprue cup towards said inner cavity, a first detector means for measuring the level of said surface and for generating a first analog signal corresponding to said level, a second detector means for measuring the width of said stream and for generating a second analog signal corresponding to said width;
• an electronic circuit means having a first input connected to said first detector means for receiving said first analog signal, a second input connected to said second detector means for receiving said second analog signal and an output;
• flow cut-off control means for causing said casting ladle to cease filling said sprue cup;
• and a connection means disposed between said output and said flow cut-off control means, said electronic circuit means comprising differentiation means, summing means and amplification means, said electronic circuit means processing both of said analog signals and forming a filling control signal from both of said processed analog signals, said filling control signal representing the flow rate of molten metal through said sprue cup, said filling control signal having an abrupt fluctuation when the flow rate of molten metal through said sprue cup undergoes an abrupt change indicating that said molten metal ceases to flow from said sprue cup into said cavity while said stream is not cut-off, whereupon said signal exceeds a predetermined threshold and actuates said flow cut-off control means.