Force sensing control apparatus and method for electric arc furnaces

In an electric arc furnace:

• a. an electrode system comprising an electrode projecting into said furnace and electrode support structure supported for movement relative to said furnace;
• b. drive means for movably positioning said electrode system relative to said furnace;
• c. force sensing means cooperating with said electrode system for detecting changes in forces applied to said electrode system and producing force signals which vary in relation to changes in the detected force;
• and,
• d. force responsive control means for said drive means, said force responsive control means comprising:
• i. control means responsive to force signal changes indicative of an obstruction to movement of said system downwardly relative to said furnace for terminating operation of said drive means;
• and,
• ii. compensating means for detecting force signal changes indicative of force changes on said system resulting from electrode consumption or electrode system position changes and preventing termination of operation of said drive means in response to such changes in force signal levels.

In an electric arc furnace:

• a. an electrode system comprising an electrode projecting into said furnace and electrode support structure supported for movement relative to said furnace;
• b. drive means for movably positioning said electrode system relative to said furnace;
• c. force sensing means cooperating with said electrode system for detecting changes in forces applied to said electrode system and producing force signals which change in relation to changes in the detected force;
• and,
• d. force responsive control means for said drive means effective to terminate operation of said drive means in response to force signal changes related to a detected change in force resisting electrode system movement having at least a predetermined rate of change of magnitude with respect to time and which is indicative of an obstruction to movement of said electrode system toward said furnace.

In an electric arc furnace:

• a. an electrode system comprising an electrode projecting into said furnace and electrode support structure supported for movement relative to said furnace;
• b. drive means for movably positioning said electrode system relative to said furnace;
• c. force sensing means cooperating with said electrode positioning system for detecting changes in forces applied to said electrode system and producing electrical force signals which vary in accordacne with changes in the magnitude, sense direction and rate of change of magnitude with respect to time of detected force changes;
• and,
• d. force responsive control means for said drive means, said force responsive control means comprising:
• i. control means responsive to force signal variations caused by force changes of a predetermined sense direction and having at least a predetermined rate of change of mangitude with respect to time for terminating operation of said drive means, said force changes being indicative of an obstruction to movement of said electrode system toward said furnace;
• and,
• ii. compensating means for detecting force signal variations caused by force changes in said predetermined sense direction having less than said predetermined rate of change of magnitude with respect to time and preventing operation of said control means in response to such variations.

A method of controlling movement of an electrode system in an electric arc furnace system comprising:

• a. moving the electrode system relative to a furnace charge;
• b. sensing changes in forces acting on the electrode system;
• c. producing a force signal having values which vary in accordance with the direction of force changes acting on said electrode system and the rate of change of magnitude with respect to time of said force changes;
• d. producing a compensating signal corresponding to force changes acting on the electrode system in a direction away from the furnace charge having less than a predetermined rate of change of magnitude with respect to time;
• e. comparing said force signal and said compensating signal;
• and,
• f. controlling movement of the electrode system toward the furnace charge in accordance with the compared relationship between said force signal and said compensating signal.

A method of controlling movement of an electrode system in an electric arc furnace system to minimize breakage of the electrode comprising:

• a. positioning the electrode system relative to a furnace charge;
• b. sensing changes in forces acting on the electrode system;
• c. discriminating between first sensed force changes resulting from force acting on the electrode system in a direction away from the furnace charge and having at least a predetermined rate of change of magnitude with respect to time and second force changes resulting from other forces acting on the electrode system;
• and,
• d. preventing motion of the electrode system toward the furnace charge in response to said first sensed force changes.