In the process of rolling conical workpiece, the workpiece must meet the following requirements when rotating: the big end and the small end of the workpiece should rotate and curl at the same angular velocity, and the linear velocity at both ends should be proportional to its diameter, that is, the linear velocity at the big end is large and the linear velocity at the small end is small. However, when the general plate bending machine works, the angular velocity and linear velocity at both ends are the same, which can not meet the requirements of conical forming. In order to make the two ends of the workpiece rotate at different linear speeds, it is necessary to replace the three large shafts on the plate bending machine with cone shafts. In order to save materials and cost, three conical sleeves are installed on the original three shafts, and then the three shafts are adjusted to a certain angle, so that the workpiece can be processed completely in line with the requirements of the drawing. This method has the advantages of smooth arc, good quality and high efficiency. For products with different cones, the cone sleeve can be replaced at any time, which expands the application scope of the machine tool.