Four-roll sizing and reducing mill

The invention discloses a novel four-roll sizing and reducing mill. Four groups of identical and replaceable roll assemblies which are installed in roll racks are arranged at 90-degree angles and driven by a motor through a speed reducer respectively. Roll shafts in the roll racks incline at certain degrees, such as 22.5 degrees, relative to the horizontal or vertical plane, simultaneously, adjacent racks can mutually turn over for 180 degrees, namely, the i rack can be used as the i+1 rack after being rotated at 180 degrees around the rolling axis horizontally or vertically. Roll gaps of adjacent racks right coincide or approximately coincide with roll bottoms, the rolling efficiency and the closure of hole patterns are greatly improved, and the product accuracy is high.