Spinning forming method

A spinning forming method comprising:

• using a plate including a central portion and a peripheral portion, the central portion being supported by a receiving jig, the peripheral portion being not directly supported by the receiving jig, and a ring-shaped projection being provided at the peripheral portion and projecting toward one side in a thickness direction of the plate;
• and
• while rotating the plate, locally heating a transform target portion of the plate and forming a forming region of the plate into a tapered shape by pressing a processing tool that is arranged radially at or inward from the projection against the transform target portion from an opposite side of the one side, the forming region spreads from a forming start position to a forming end position, the forming start position is located away from the receiving jig, and the forming end position is located at a radially outer side of the forming start position,
• and
• during the pressing, the forming region of the plate is not directly supported by the receiving jig.