Vacuum furnace

Claim 1

IN A FURNACE FOR SUBJECTING A WORK PIECE TO HEAT IN A CONTROLLED ATMOSPHERE, THE FURNACE HAVING OUTER INSULATING WALL MEANS SPACED FROM AND ENCLOSING A HEAT-CONDUCTIVE RETORT, THE WALL MEANS AND THE RETORT DEFINING THEREBETWEEN AN OUTER HEATING CHAMBER, AND THE RETORT ENCLOSING AN INNER HEATING CHAMBER SURROUNDING A CENTRAL WORK-SUPPORTING MEANS FOR RECEIVING THE WORK PIECE; THE IMPROVEMENTS OF MEANS FOR MAINTAINING A CONTROLLED ATMOSPHERE IN SAID INNER CHAMBER, A PRIMARY HEATING MEANS IN SAID INNER CHAMBER, A SECONDARY HEATING MEANS IN SAID OUTER CHAMBER, THERMOSTATIC MEANS RESPONSIVE TO THE TEMPERATURE OF SAID RETORT TO CONTROL SAID SECONDARY HEATING MEANS, ADDITIONAL THERMOSTATIC MEANS RESPONSIVE TO THE TEMPERATURE OF THE WORK PIECE TO CONTROL SAID PRIMARY HEATING MEANS, AND HEAT-REFLECTIVE BAFFLE MEANS DISPOSED ABOUT SAID WORK-SUPPORTING MEANS AND INTERPOSED BETWEEN SAID RETORT AND SAID PRIMARY HEATING MEANS (1) TO REFLECT HEAT FROM THE PRIMARY HEATING MEANS ONTO THE WORK PIECE AND (2) TO CAUSE A TEMPERATURE GRADIENT BETWEEN THE PRIMARY HEATING MEANS AND SAID RETORT.