Carburizing method and apparatus

Claim 1

IN A CONTINUOUS METHOD FOR CARBURIZING FERROUS METAL WORK WHICH INCLUDES THE STEPS OF PASSING THE WORK SUCCESSIVELY THROUGH LONGITUDINALLY EXTENDING AND ALIGNED HEATING, CARBURIZING, AND DIFFUSING ZONES WHILE MAINTAINING A TEMPERATURE BETWEEN 1350* F. AND 1800* F. IN EACH OF THE ZONES, THE IMPROVEMENT OF CONTROLLING THE CARBON POTENTIAL OF THE CARBURIZING ZONE BETWEEN 0.6 AND 1.4 PERCENT AND DIFUSSING ZONE BETWEEN 0.6 AND 1.1 PERCENT BY CAUSING ATMOSPHERE FLOW IN ONE DIRECTION WHILE PREVENTING SUCH FLOW IN THE OPPOSITE DIRECTION BETWEEN THE TWO, INTRODUCING INTO THE HEATING ZONE A CARRIER GAS INCAPABLE OF APPRECIABLE CARBURIZATION OF THEWORK, PREVENTING APPRECIABLE FLOW OF THE CARRIER GAS EXCEPT IN THE DIRECTION OF WORK MOVEMENT THROUGH THE HEATING ZONE AND INTO THE CARBURIZING ZONE, MIXING WITH THE ATMOSPHERE WHICH FLOWS INTO THE CARBURIZING ZONE FROM AT LEAST ONE OF THE OTHER ZONES AN ENRICHING GAS IN A PROPORTION TO PROVIDE THE CARBON POTENTIAL DESIRED THEREIN, PREVENTING APPRECIABLE FLOW OF ATMOSPHERE FROM THE CARBURIZING ZONE AN ATMOSPHERE WHICH, WHEN MIXED WITH ANY ATMOSPHERE FLOWING INTO THE DIFFUSING ZONE FROM THE CARBURIZING ZONE, PROVIDES THE ATMOSPHERE REQUIRED THEREIN, AND WITHDRAWING ATMOSPHERE FROM THE ONE OF THE CARBURIZING AND DIFFUSING ZONES TOWARD WHICH ATMOSPHERE FLOWS FROM THE OTHER AT SUBSTANTIALLY THE RATE AT WHICH ATMOSPHERE IS INTRODUCED INTO THE SEVERAL ZONES.