CORE METAL FOR EXPANDING DIAMETER OF RING AND METHOD FOR EXPANDING DIAMETER OF RING USING THIS

摘要

PROBLEM TO BE SOLVED: To reduce number of core metals for expanding the diameter of a ring and to shorten the time of changing work of the core metal by forming the core metal for expanding the diameter of the ring to plural curving surfaces having different curvature radiuses in the outer peripheral direction. ;SOLUTION: The core metal A for expanding the diameter of the ring is formed as four curving surfaces 1, 2, 3, 4 having the different curvature radiuses in the outer peripheral direction. The sizes of the curvature radiuses are made to R₁R₂R₃R₄ and suitably selected according to the expanding diameter ratio of an annular body to expand the diameter. Further, the lengths L of the curving surfaces 1, 2, 3, 4 are suitably selected and this length can be the same length as the length of a press in the max. length.;COPYRIGHT: (C)1997,JPO