The structure of this machine is a three roll symmetrical type. The upper roll performs vertical lifting and lowering motion at the symmetrical positions of the two lower rolls, which is obtained through the transmission of a screw and a mother screw. The two lower rolls rotate and provide torque for the rolled plate through the output gear of the reducer and the lower roll gear. The disadvantage of this machine is that the end of the plate needs to be pre bent with the help of other equipment.