Furnace of decreasing oxygen concentration to ultra low amount

A furnace with an ultra low amount of oxygen concentration, comprising an inlet;

• an outlet;
• a plurality of zones between said inlet and said outlet;
• means for supplying a non-oxidizing gas into each of said plurality of zones to increase an internal pressure therein;
• shutter means at least at an inlet and an outlet of said furance for checking flow of air into said furnace;
• control means for controlling operation of said shutter means;
• means for transferring a workpiece through said furnace and including a transferring arrangement for transferring the workpiece between said plurality of zones, said transferring arrangement having a speed which is lower than speeds of workpiece transferring elements located at said inlet and said outlet whereby opening time of said shutter means is reduced;
• and a plurality of partitions for separating said plurality of zones, each of said plurality of partitions having opening means having a predetermined size corresponding to the size of the workpiece for passing the workpiece through said partitions, said transferring arrangement comprising a plurality of independently operating endless conveyors corresponding in number to a number of zones in said plurality of zones, each of said plurality of endless conveyors having means projecting transverse to a path of movement of the workpiece for supporting the workpiece at both sides of the workpiece during transfer of the workpiece through said plurality of zones with the upper surface of the workpiece being exposed to an atmosphere in said plurality of zones.