Roll trigger to the top roller the two bottom rollers through the central symmetry position within the hydraulic cylinder piston hydraulic oil in the role of vertical lifting movement, through the main reducer gear driving the last stage of the two bottom rollers gear meshes cooperation rotational motion, for coiling sheet provides torque. Polishing-edge specifications flat plastic sheet metal through polishing-edge three roots of work roll (2 roots roller, a piece of the top roller) between the press, with the help of the top roller and bottom rollers to the rotary motion, the metal plate after multipass continuou bending, produce the permanent deformation, roll made needed garden cylinder, cones or part of them. This hydraulic type three rollers polishing-edge shortcoming is plank ends need some other equipment preflex. This polishing-edge applies to coil plate thickness in more than 50 large polishing-edge, the two bottom rollers increased a row of fixed roller, shorten the two bottom rollers span, so as to improve the coiling workpiece precision and machine overall performance.