Cylindrical member and manufacturing method therefor

A manufacturing method for manufacturing a cylindrical member, comprising:

• a preparation step of preparing a cylindrical workpiece material;
• and
• a processing step of forming, in a circumferential wall of the workpiece material, a bead that has a shape inwardly protruding in a radial direction of the workpiece material and that extends in a circumferential direction of the workpiece material by pressing the workpiece material in an axial direction of the workpiece material by an axial press die, and pressing, into the circumferential wall, a plate die disposed outside of the circumferential wall in the radial direction while rotating the workpiece material about a central axis relative to the plate die,
• wherein, in a cross-sectional view taken along a thickness direction of the plate die, the plate die includes:
• a first surface that extends in the radial direction and has a linear shape;
• a second surface that is located on a side opposite to the first surface, extends in the radial direction, and has a linear shape;
• and
• an end surface that connects the first surface and the second surface, faces the circumferential wall, and includes an arc-shaped first shoulder portion continuous with the first surface and an arc-shaped second shoulder portion continuous with the second surface, and
• when a radius of curvature of each of the first shoulder portion and the second shoulder portion is represented by Rp, a plate thickness of the circumferential wall is represented by t, and a pressing amount of the plate die in the processing step is represented by X, Rp, t, and X satisfy formulae (1) and (2) below:
• 0.2
• ≤
• Rp
• /
• t
• (
• 1
• )
• X
• /
• Rp
• ≤
• 20.5
• .
• (
• 2
• )