FORGING METHOD FOR CRANK SHAFT

摘要

PURPOSE:To reduce a remarkable man-hour with the forging stage of an axially asymmetrical intermediate forming item as one stage by performing the distribution of the blank stock metal in the axial and diameter directions by the rolling action of >=2 dies. CONSTITUTION:The eccentric forming part 5b like both the parts becoming asymmetrical in case of the axial center of an intermediate forming item P is made symmetrical is formed on a pair of roller dies used as a roller die method in a performing stage. The intermediate forming item P is formed with a blank stock W1 being rotated with being regulated in its position by a work rest 6 as well by pinching the blank stock W1 in a round bar shape with both dies 3, 4 and by symmetrically rotating both dies in the same direction by conforming the biting lead-in part of both roller dies 3, 4. Namely, the distribution of the blank stock metal volume in the axial direction and diameter direction and eccentric bending are simultaneously performed. The intermediate forming item P is comparatively faithful to the final product shape, so the volume of an excess metal part F is small and the yield can be improved as well.