Annular thin-wall part forming method, forming mold and forming stamping tool

The invention discloses an annular thin-wall part forming method. The forming method is applied to a columnar blank material, and comprises the following steps of head part upsetting, hole extruding and thin-wall part extruding, wherein upsetting is conducted on one end of an initial blank material section to form a head part, the initial blank material section forms a stepped shaft-shaped blank material section, and hole upsetting is simultaneously conducted on the end surface of one end of the initial blank material section in the process of initial blank material section upsetting, so thatan initial positioning hole is formed in the end surface in the head part upsetting step; the initial positioning hole is extruded and stretched, so that the axial dimension of the stepped shaft-shaped blank material section becomes larger, in addition, the initial positioning hole becomes longer and forms a long positioning hole, and the axial dimension of the head part becomes larger, wherein the to-be-deformed volume r