Automatic screening device for size of crushed ore

The utility model relates to the technical field of ore mechanical equipment manufacturing, in particular to an automatic crushed ore size screening device which comprises a machine frame, a screening mechanism is arranged on the machine frame, the screening mechanism comprises a shell which is fixed on the machine frame in a downward inclined mode, and a screening cage is rotatably installed in the shell. The screening cage is formed by splicing a plurality of screening units, each screening unit comprises a screening shell, every two adjacent screening shells are fixedly connected through a lock catch, the section of each screening shell is in an annular shape, a plurality of screening holes are formed in the surface of each screening shell, a bearing frame is horizontally fixed to the interior of each screening shell, and a first rotating shaft is rotationally installed on each bearing frame; a spiral blade is fixed to the first rotating shaft, a hexagonal prism is fixed to one end of the first rotating sh