Induction strip heating apparatus

Claim 1

IN A THERMAL TREATMENT PROCESS FOR A METAL STRIP, THE STEPS OF PASSING THE STRIP CONTINUOUSLY THROUGH A TREATMENT ZONE DEFINED BY FIRST AND SECOND ELECTRICAL CONTACTS SPACED FROM EACH OTHER IN THE DIRECTION OF STRIP TRAVEL, CAUSING CURRENT TO FLOW THROUGH A CIRCIUT INCLUDING THE STRIP, THE FIRST AND SECOND CONTACTS AND A RETURN CONDUCTOR BETWEEN THE CONTACTS, BY INDUCING A POTENTIAL GRADIENT LONGITUDINALLY OF THE STRIP AND OF SUFFICIENT INTENSITY TO INCREASE THE STRIP TEMPERATURE TO A DESIRED VALUE AT A POINT INTERMEDIATE SAID FIRST AND SECOND CONTACTS, SHIELDING THE STRIP FROM COOLING BETWEEN SAID FIRST CONTACT AND SAID POINT AT WHICH DESIRED TEMPERATURE IS REACHED, AND APPLYING REGULABLE COOLING BETWEEN SAID POINT AND SAID, SECOND CONTACT TO REMOVE HEAT FROM THE STRIP AT A RATE SUBSTANTIALLY AS GREAT AS THE RATE OF HEAT LIBERATION, THEREBY MAINTAINING THE TEMPERATURE OF THE STRIP WITHOUT SUBSTANTIAL INCREASE AT THE DESIRED TEMPERATURE REGARDLESS OF HEAT LIBERATED THEREIN, AFTER SUCH DESIRED TEMPERATURE IS REACHED.