Patent ID: 7299670

Claim:
A production method of a cylindrical component having a bent portion through rolling by pushing rolls to a cylindrical work obtained from a pipe material, comprising: a clamping step of clamping a cylindrical work with a pair of molds, an end portion of the work being accommodated in a ring-like recess in a first of the pair of molds, wherein a projection is provided on an inner edge of the ring-like recess and a slope is formed from the projection to an internal circumference of the first of the pair of molds so as to increase a distance from the second of the pair of molds, the second of the pair of molds having an inserting portion arranged inside the work; a preparatory molding step of advancing a preparatory molding roll having a push surface shaped into a convex shape on an outer peripheral surface thereof and pushing it to an outer peripheral surface of the work so that the prepatory molding roll is located below the projection and the work is sandwiched between the molding roll and the projection while said work is chucked by the pair of molds and is rotated by applying axial propelling force, to bend inward the outer peripheral surface of said work in a radial direction, a ring-like step portion being formed on a tip of the inserting portion to define a bent portion of the work; and a crush-molding step of clamping the sheet thickness of said work by said preparatory molding roll and said pair of molds, a gap between the slope and the second of the pair of molds, and a space on a corner of the step portion, being dead pockets, then moving back said preparatory molding roll and crushing said work in the axial direction to form the bent portion.