A steel mill is a machine used to change the shape and size of steel materials by pressure, and the main body of the mill is a complete set of equipment for rolling and rolling metal billets into materials. The rolling mill is the main machine for rolling metal directly, it uses the rotating rolls to roll the billet to make the metal plastic deformation according to the specified requirements. Rolling is the highest productivity, the lowest cost metal forming method, suitable for rolling the same cross-section or periodic changes in the strip or plate material; special rolling mill can roll mechanical parts or their blanks and some non-metallic materials. According to the different processing temperatures are divided into hot rolling mill and cold rolling mill. Hot rolling is rolled under the condition of heating the rolled parts to reduce the rolling pressure. Cold rolling is carried out at room temperature, which can make the rolled parts get high shape and size accuracy and surface finish, and can improve the mechanical properties of the rolled parts. According to the different shapes are divided into profile mills, strip mills, bar and wire rolling mills, pipe mills, etc. The composition of the mill. The mill consists of the main motor, the main drive and the main seat (work seat). The main motor in the need for speed control when using DC motors, do not need to speed control when using synchronous or asynchronous (with flywheel) AC motor. The main base consists of the frame, rolls, bearing seat, press down device and balancing device and other groups. The frame is to bear the rolling force of the components, closed frame has a better rigidity, but the open frame is more convenient to change rolls. Roll is the rolling metal parts, the roll body for the work part, the shaft head for transmission. The shape of the roll body of the plate roll is called the roll type, and the groove of the profile roll is called the hole type. Pressing down device is used to adjust the amount of rolls pressed down. High-speed strip mill thickness self-control is often done by the hydraulic pressure device. Balancing device is used to eliminate the impact of clearance at the press down screws, etc., to avoid impact when loaded. The main block of the strip mill is also equipped with a hydraulic bending roll device to apply additional bending moment in the roll neck and additional deflection of the roll body, in order to control the lateral thickness of the strip and obtain the best plate shape. Steel rolling process. The general production process of a steel mill is: the general process is: loading mechanism - heating furnace - descaling machine - rough rolling unit - medium rolling unit - finishing unit - segmental shear - on the cold bed brake - cold bed - finished shear or saw - finishing and baling device. Finishing device according to different products will be very different, high wire to have a spitting machine into the coil station, cooling line, baling machine, etc., special steel requires chamfering, grinding, flaw detection and other process equipment.