Oil well cement shearing and mixing device

The invention discloses an oil well cement shearing and mixing device which comprises a mixing bin, a storage bin and an external power shaft, wherein a feeding hole and a feeding hole flashboard are arranged at and formed in the top of the mixing bin; the feeding hole flashboard is used for adjusting the size of the feeding hole through a flashboard handle which is positioned on the side of the mixing bin; at least one roll shaft is horizontally arranged in the mixing bin; a plurality of helical blades are fixed on the roll shafts in sequence; one ends of the roll shafts penetrate through the side surface of the mixing bin to be connected with a power shaft through gears; the other ends of the roll shafts are adjacent to the inlet of the storage bin; a flashboard which is used for controlling the opening and closing of the inlet of the storage bin is arranged on the inlet of the storage bin; a crank arm is arranged in the storage bin; the turning part of the crank arm is suspended on the inner shell of the storage bin through a pin shaft; one end of the crank arm is pinned at the center of the flashboard; a heavy hammer which is capable of sliding along the crank arm is pinned at the other end of the crank arm; through the sliding of the heavy hammer along the crank arm, the compression degree from the flashboard to the feeding hole is adjusted; the pneumatic diffusing and mixing is replaced by mechanical shearing and mixing, so that the mixing can be uniform and the layering can be avoided.