Full-automatic forced convection type grain drying machine

The utility model discloses a full-automatic forced convection type grain drying machine which comprises a variable-diameter hopper, a conveying pipe is fixed to the outer end of the variable-diameter hopper, a trapezoidal barrel is fixedly welded to the outer surface of the conveying pipe through a welding block, a motor is fixed to the surface of the upper end of the conveying pipe, and a conveying shaft is fixed to the end face of a driving shaft of the motor. Spiral lifting blades are fixed to the outer surface of the conveying shaft, an inclined guide pipe is arranged at the upper end of the conveying pipe, a movable joint pipe is fixed to the end face of the inclined guide pipe, an inlet is formed in the surface of the trapezoidal barrel, the movable joint pipe is inserted into the inlet, inclined convex openings are formed in the upper end and the lower end of the trapezoidal barrel, and air heaters are fixed outside the inclined convex openings; by adopting spiral conveying, the drying comprehensivene