The machine adopts 3-roller symmetrical structure with the upper roller as the main drive and the lower roller makes vertical movement so as to clamp the plate materials tight. The main drive comes from the engagement between the gear of the lower roller and the gear of the upper roller. The side roller makes elevating movements and has the function of preliminary bending and rolling. The disadvantage of the machine is that the ends of the plate materials need other equipment for pre-bending.