The main working parts and tools for continuous plastic deformation of metal on a rolling mill. The roll is mainly composed of roll body, roll neck and shaft head. The roll body is the middle part of the roll which is actually involved in rolling metal. It has a smooth cylindrical or grooved surface. The roll neck is installed in the bearing and the rolling force is transmitted to the frame through the bearing housing and the press-down device. The shaft head of the transmission end is connected with the gear base through the connecting shaft, and the rotation moment of the motor is transferred to the roll. The rolls can be arranged in the form of two, three, four or more rolls in the mill frame. There are various classification methods for rollers, mainly including: (1) According to product type, there are strip roll, section roll, wire roll, etc. (2) According to the position of the roll in the rolling mill series, there are blank roll, rough roll, finishing roll, etc.; (3) According to the roll function, there are scale-breaking roller, perforating roller, leveling roller, etc.; (4) According to the roll material is divided into steel roll, cast iron roll, carbide roll, ceramic roll, etc.; (5) According to the manufacturing method, it can be divided into casting roll, forging roll, surfacing roll, sleeve roll, etc.; (6) According to the state of rolled steel, there are hot roll, cold roll. The various classifications may be combined to give a more specific meaning to the roll, such as the centrifugal cast high chromium cast iron working roll for hot rolled strip steel.