Heat-treating furnace

A heat-treating furnace having:

• a rotary shaft;
• a rotary bottom surface, the rotary bottom surface being pivotally supported by the rotary shaft and rotating;
• a plurality of workpiece storage chambers arranged on the rotary bottom surface in a multi-stage torus configuration around an axis of the rotary shaft as a center;
• a hollow bell-shaped hot-blast guide disposed in a center of the torus configuration on the rotary bottom surface around the axis of the rotary shaft as a center so as to decrease a volumetric capacity in the furnace and to adjust a quantity of a hot blast fed in from above the hollow bell-shaped hot-blast guide into the workpiece storage chamber on each stage;
• a furnace body bottom surface spaced away from the rotary bottom surface;
• and
• a furnace body lateral surface disposed on the furnace body bottom surface,
• wherein the furnace body bottom surface is configured to have a downward taper from the rotary shaft toward an outer wall surface, and
• a dust discharge port is provided immediately below the outer wall surface.