Patent ID: 8091396
Filing Date: 2012-01-10
Classification: B21D

Abstract:
1. A method for forming an end portion of a cylindrical workpiece by a spinning process, with the cylindrical workpiece and at least one roller being relatively moved, and with the roller being rotated relative to the cylindrical workpiece, in such a state as being held to be in contact with each other, comprising: performing a first relative motion of the roller against the cylindrical workpiece toward one open extremity thereof; performing a second relative motion of the roller against at least a part of outer peripheral surface of the end portion of the cylindrical workpiece toward an inside of the cylindrical workpiece, so as to be close thereto or remote therefrom, while the roller is rotated relative to the cylindrical workpiece by one rotation, in such a state as being held to be in contact with the end portion of the cylindrical workpiece, in a plane perpendicular to the moving direction of the first relative motion, the plane including a position where the roller contacts the outer peripheral surface of the end portion of the cylindrical workpiece; performing a rotational motion of the roller, relatively rotating around the cylindrical workpiece by performing the second relative motion, with the roller being held to be in contact with the outer peripheral surface of the end portion of the cylindrical workpiece on the perpendicular plane; and performing the first relative motion from the contacting position up to a position exceeding the one open extremity of the cylindrical workpiece, while repeating the second relative motion and the rotational motion; wherein a motion cycle including the first relative motion, second relative motion and rotational motion is repeated by a plurality of cycles, so as to form a part of a deformed axial cross section, the deformed axial cross section consequently possessing non-rotation symmetry, on the end portion of the cylindrical workpiece.